diff --git a/hphp/compiler/analysis/control_flow.cpp b/hphp/compiler/analysis/control_flow.cpp
index 3acd9487a..15590ec7d 100644
--- a/hphp/compiler/analysis/control_flow.cpp
+++ b/hphp/compiler/analysis/control_flow.cpp
@@ -868,7 +868,7 @@ ControlFlowGraph *ControlFlowGraph::buildControlFlow(MethodStatementPtr m) {
   ControlFlowGraph *graph = new ControlFlowGraph;
 
   graph->m_stmt = m;
-  ControlFlowBuilder cfb(graph, m->getOrigGeneratorFunc());
+  ControlFlowBuilder cfb(graph, !!m->getOrigGeneratorFunc());
   cfb.run(m->getStmts());
   graph->m_nextDfn = 1;
   depth_first_visit(*graph, cfb.head(),
diff --git a/hphp/compiler/analysis/emitter.cpp b/hphp/compiler/analysis/emitter.cpp
index 0c1a17ba8..7520dcbe1 100644
--- a/hphp/compiler/analysis/emitter.cpp
+++ b/hphp/compiler/analysis/emitter.cpp
@@ -14,6 +14,13 @@
    +----------------------------------------------------------------------+
 */
 
+#include "folly/ScopeGuard.h"
+
+#include <iostream>
+#include <iomanip>
+#include <vector>
+#include <algorithm>
+
 #include <util/logger.h>
 #include <util/util.h>
 #include <util/job_queue.h>
@@ -96,11 +103,6 @@
 
 #include <system/lib/systemlib.h>
 
-#include <iostream>
-#include <iomanip>
-#include <vector>
-#include <algorithm>
-
 namespace HPHP {
 namespace Compiler {
 ///////////////////////////////////////////////////////////////////////////////
@@ -3826,7 +3828,7 @@ bool EmitterVisitor::visitImpl(ConstructPtr node) {
         pce->addMethod(invoke);
         MethodStatementPtr body(
           static_pointer_cast<MethodStatement>(ce->getClosureFunction()));
-        invoke->setHasGeneratorAsBody(body->getGeneratorFunc());
+        invoke->setHasGeneratorAsBody(!!body->getGeneratorFunc());
         postponeMeth(body, invoke, false, new ClosureUseVarVec(useVars));
 
         return true;
@@ -5173,7 +5175,7 @@ void EmitterVisitor::emitPostponedMeths() {
       fe = new FuncEmitter(m_ue, -1, -1, methName);
       fe->setIsGenerator(funcScope->isGenerator());
       fe->setIsGeneratorFromClosure(funcScope->isGeneratorFromClosure());
-      fe->setHasGeneratorAsBody(p.m_meth->getGeneratorFunc());
+      fe->setHasGeneratorAsBody(!!p.m_meth->getGeneratorFunc());
       p.m_fe = fe;
       top_fes.push_back(fe);
     }
@@ -7459,7 +7461,7 @@ Unit* hphp_compiler_parse(const char* code, int codeLen, const MD5& md5,
       filename = "";
       unitOrigin = UnitOriginEval;
     }
-    ScopeGuard sg(SymbolTable::Purge);
+    SCOPE_EXIT { SymbolTable::Purge(); };
 
     // Check if this file contains raw hip hop bytecode instead of php.
     // For now this is just dictated by file extension, and doesn't ever
diff --git a/hphp/compiler/analysis/function_scope.cpp b/hphp/compiler/analysis/function_scope.cpp
index 4cd90f24b..c5eb2e5dd 100644
--- a/hphp/compiler/analysis/function_scope.cpp
+++ b/hphp/compiler/analysis/function_scope.cpp
@@ -342,12 +342,12 @@ bool FunctionScope::isGenerator() const {
          (ParserBase::IsContinuationName(name()) &&
           m_paramNames.size() == 1 &&
           m_paramNames[0] == CONTINUATION_OBJECT_NAME));
-  return getOrigGenStmt();
+  return !!getOrigGenStmt();
 }
 
 bool FunctionScope::hasGeneratorAsBody() const {
   MethodStatementPtr stmt = dynamic_pointer_cast<MethodStatement>(getStmt());
-  return stmt ? stmt->getGeneratorFunc() : false;
+  return stmt ? !!stmt->getGeneratorFunc() : false;
 }
 
 bool FunctionScope::isGeneratorFromClosure() const {
diff --git a/hphp/compiler/analysis/variable_table.cpp b/hphp/compiler/analysis/variable_table.cpp
index 208fd9c13..6ce3f3376 100644
--- a/hphp/compiler/analysis/variable_table.cpp
+++ b/hphp/compiler/analysis/variable_table.cpp
@@ -744,7 +744,7 @@ static bool by_location(const VariableTable::StaticGlobalInfoPtr &p1,
                         const VariableTable::StaticGlobalInfoPtr &p2) {
   ConstructRawPtr d1 = p1->sym->getDeclaration();
   ConstructRawPtr d2 = p2->sym->getDeclaration();
-  if (!d1) return d2;
+  if (!d1) return !!d2;
   if (!d2) return false;
   return d1->getLocation()->compare(d2->getLocation().get()) < 0;
 }
diff --git a/hphp/runtime/base/program_functions.cpp b/hphp/runtime/base/program_functions.cpp
index c08886d6a..1589e484d 100644
--- a/hphp/runtime/base/program_functions.cpp
+++ b/hphp/runtime/base/program_functions.cpp
@@ -13,9 +13,9 @@
    | license@php.net so we can mail you a copy immediately.               |
    +----------------------------------------------------------------------+
 */
+#include "runtime/base/program_functions.h"
 
 #include "runtime/base/types.h"
-#include "runtime/base/program_functions.h"
 #include "runtime/base/type_conversions.h"
 #include "runtime/base/builtin_functions.h"
 #include "runtime/base/execution_context.h"
@@ -618,7 +618,7 @@ static int start_server(const std::string &username) {
     Logger::Info("Replaying warmup request %s", file.c_str());
     try {
       rt.onRequestStart(start);
-      rt.replayInput(file);
+      rt.replayInput(Hdf(file));
       handler.handleRequest(&rt);
       Logger::Info("Finished successfully");
     } catch (std::exception& e) {
diff --git a/hphp/runtime/base/server/satellite_server.cpp b/hphp/runtime/base/server/satellite_server.cpp
index 670376736..e57c2f8fb 100644
--- a/hphp/runtime/base/server/satellite_server.cpp
+++ b/hphp/runtime/base/server/satellite_server.cpp
@@ -45,7 +45,7 @@ SatelliteServerInfo::SatelliteServerInfo(Hdf hdf) {
   hdf["Passwords"].get(m_passwords);
   m_alwaysReset = hdf["AlwaysReset"].getBool(false);
 
-  string type = hdf["Type"];
+  string type = hdf["Type"].getString();
   if (type == "InternalPageServer") {
     m_type = SatelliteServer::KindOfInternalPageServer;
     vector<string> urls;
@@ -99,7 +99,7 @@ private:
 
 class InternalPageServer : public SatelliteServer {
 public:
-  InternalPageServer(SatelliteServerInfoPtr info) {
+  explicit InternalPageServer(SatelliteServerInfoPtr info) {
     InternalPageServerImplPtr server
       (new TypedServer<InternalPageServerImpl, HttpRequestHandler>
        (RuntimeOption::ServerIP, info->getPort(), info->getThreadCount(),
@@ -124,7 +124,7 @@ private:
 
 class DanglingPageServer : public SatelliteServer {
 public:
-  DanglingPageServer(SatelliteServerInfoPtr info) {
+  explicit DanglingPageServer(SatelliteServerInfoPtr info) {
     m_server = ServerPtr
       (new TypedServer<LibEventServer, HttpRequestHandler>
        (RuntimeOption::ServerIP, info->getPort(), info->getThreadCount(),
@@ -185,7 +185,7 @@ private:
 
 class RPCServer : public SatelliteServer {
 public:
-  RPCServer(SatelliteServerInfoPtr info) {
+  explicit RPCServer(SatelliteServerInfoPtr info) {
     m_server = ServerPtr(new RPCServerImpl(RuntimeOption::ServerIP, info));
   }
 
diff --git a/hphp/runtime/ext/ext_mysql.cpp b/hphp/runtime/ext/ext_mysql.cpp
index 59d6195de..aed19c9f3 100644
--- a/hphp/runtime/ext/ext_mysql.cpp
+++ b/hphp/runtime/ext/ext_mysql.cpp
@@ -15,6 +15,8 @@
    +----------------------------------------------------------------------+
 */
 
+#include "folly/ScopeGuard.h"
+
 #include <runtime/ext/ext_mysql.h>
 #include <runtime/ext/ext_preg.h>
 #include <runtime/ext/ext_network.h>
@@ -1443,7 +1445,7 @@ Variant f_mysql_async_wait_actionable(CVarRef items, double timeout) {
   }
 
   struct pollfd* fds = (struct pollfd*)calloc(count, sizeof(struct pollfd));
-  ScopeGuard fds_free([fds]() { free(fds); });
+  SCOPE_EXIT { free(fds); };
 
   // Walk our input, determine what kind of poll() operation is
   // necessary for the descriptor in question, and put an entry into
diff --git a/hphp/util/alloc.cpp b/hphp/util/alloc.cpp
index 17563dc59..29e0aee89 100644
--- a/hphp/util/alloc.cpp
+++ b/hphp/util/alloc.cpp
@@ -13,15 +13,15 @@
    | license@php.net so we can mail you a copy immediately.               |
    +----------------------------------------------------------------------+
 */
+#include "util/alloc.h"
 
 #include <atomic>
 
-#include "alloc.h"
 #include <sys/mman.h>
 #include <stdlib.h>
 #include <errno.h>
-#include "util.h"
-#include "logger.h"
+#include "util/util.h"
+#include "util/logger.h"
 
 namespace HPHP { namespace Util {
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/hphp/util/alloc.h b/hphp/util/alloc.h
index f8d2595d7..436ce06ce 100644
--- a/hphp/util/alloc.h
+++ b/hphp/util/alloc.h
@@ -65,8 +65,8 @@ namespace HPHP {
 
 class OutOfMemoryException : public Exception {
 public:
-  OutOfMemoryException(size_t size)
-      : Exception("Unable to allocate %zu bytes of memory", size) {}
+  explicit OutOfMemoryException(size_t size)
+    : Exception("Unable to allocate %zu bytes of memory", size) {}
   virtual ~OutOfMemoryException() throw() {}
   EXCEPTION_COMMON_IMPL(OutOfMemoryException);
 };
diff --git a/hphp/util/asm-x64.cpp b/hphp/util/asm-x64.cpp
index ab58f3f4a..994511522 100644
--- a/hphp/util/asm-x64.cpp
+++ b/hphp/util/asm-x64.cpp
@@ -13,6 +13,8 @@
    | license@php.net so we can mail you a copy immediately.               |
    +----------------------------------------------------------------------+
 */
+#include "util/asm-x64.h"
+
 #include <stdint.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -24,7 +26,6 @@
 #include <sys/types.h>
 
 #include "util/assertions.h"
-#include "util/asm-x64.h"
 #include "util/maphuge.h"
 #include "runtime/base/runtime_option.h"
 
diff --git a/hphp/util/asm-x64.h b/hphp/util/asm-x64.h
index bf978bd31..99ca32d94 100644
--- a/hphp/util/asm-x64.h
+++ b/hphp/util/asm-x64.h
@@ -79,7 +79,7 @@ struct Reg64 {
 
   // Implicit conversion for backward compatability only.  This is
   // needed to keep the store_reg##_disp_reg## style apis working.
-  constexpr operator RegNumber() const { return RegNumber(rn); }
+  constexpr /* implicit */ operator RegNumber() const { return RegNumber(rn); }
 
   // Integer conversion is allowed but only explicitly.  (It's not
   // unusual to want to printf registers, etc.  Just cast it first.)
@@ -101,7 +101,7 @@ private:
 #define SIMPLE_REGTYPE(What)                                        \
   struct What {                                                     \
     explicit constexpr What(int rn) : rn(rn) {}                     \
-    explicit constexpr operator RegNumber() const {                 \
+    explicit constexpr /* implicit */ operator RegNumber() const {  \
       return RegNumber(rn);                                         \
     }                                                               \
     explicit constexpr operator int() const { return rn; }          \
@@ -440,14 +440,6 @@ namespace reg {
 
 //////////////////////////////////////////////////////////////////////
 
-static inline void
-atomic_store64(volatile uint64_t* dest, uint64_t value) {
-  // gcc on x64 will implement this with a 64-bit store, and
-  // normal 64-bit stores don't tear across instruction boundaries
-  // assuming all 8 bytes of dest are on the same cacheline.
-  *dest = value;
-}
-
 /*
  * Note that CodeAddresses are not const; the whole point is that we intend
  * to mutate them. uint8_t is as good a type as any: instructions are
@@ -574,7 +566,12 @@ struct DataBlock {
       for (size_t i = 0; i < n; ++i) {
         u.bytes[i] = bs[i];
       }
-      atomic_store64((uint64_t*)frontier, u.qword);
+
+      // If this address doesn't span cache lines, on x64 this is an
+      // atomic store.  We're not using atomic_release_store() because
+      // this code path occurs even when it may span cache lines, and
+      // that function asserts about this.
+      *reinterpret_cast<uint64_t*>(frontier) = u.qword;
     } else {
       memcpy(frontier, bs, n);
     }
diff --git a/hphp/util/async_job.h b/hphp/util/async_job.h
index ab9879498..7c67a3f01 100644
--- a/hphp/util/async_job.h
+++ b/hphp/util/async_job.h
@@ -39,9 +39,10 @@ class WorkerInfo {
 template<class TJob, class TWorker>
 class WorkerWrapper {
 public:
-  WorkerWrapper(JobDispatcher<TJob, TWorker> &dispatcher)
-    : m_dispatcher(dispatcher),
-    m_func(this, &WorkerWrapper<TJob, TWorker>::doJob) {
+  explicit WorkerWrapper(JobDispatcher<TJob, TWorker> &dispatcher)
+    : m_dispatcher(dispatcher)
+    , m_func(this, &WorkerWrapper<TJob, TWorker>::doJob)
+  {
     if (!WorkerInfo<TJob>::DoInit) {
       m_func.setNoInit();
     }
diff --git a/hphp/util/base.h b/hphp/util/base.h
index 52f646c3d..2fbf43060 100644
--- a/hphp/util/base.h
+++ b/hphp/util/base.h
@@ -263,14 +263,18 @@ public:
   hphp_raw_ptr() : px(0) {}
   explicit hphp_raw_ptr(T *p) : px(p) {}
 
-  hphp_raw_ptr(const boost::weak_ptr<T> &p) : px(p.lock().get()) {}
+  /* implicit */ hphp_raw_ptr(const boost::weak_ptr<T> &p)
+    : px(p.lock().get())
+  {}
 
   template <class S>
-  hphp_raw_ptr(const boost::shared_ptr<S> &p) : px(p.get()) {}
+  /* implicit */ hphp_raw_ptr(const boost::shared_ptr<S> &p) : px(p.get()) {}
   template <class S>
-  hphp_raw_ptr(const boost::weak_ptr<S> &p) : px(p.lock().get()) {}
+  /* implicit */ hphp_raw_ptr(const boost::weak_ptr<S> &p)
+    : px(p.lock().get())
+  {}
   template <class S>
-  hphp_raw_ptr(const hphp_raw_ptr<S> &p) : px(p.get()) {}
+  /* implicit */ hphp_raw_ptr(const hphp_raw_ptr<S> &p) : px(p.get()) {}
 
   boost::shared_ptr<T> lock() const {
     return px ? boost::static_pointer_cast<T>(px->shared_from_this()) :
@@ -281,7 +285,7 @@ public:
   }
 
   template <class S>
-  operator boost::shared_ptr<S>() const {
+  /* implicit */ operator boost::shared_ptr<S>() const {
     S *s = px; // just to verify the implicit conversion T->S
     return s ? boost::static_pointer_cast<S>(px->shared_from_this()) :
       boost::shared_ptr<S>();
@@ -289,7 +293,7 @@ public:
 
   T *operator->() const { assert(px); return px; }
   T *get() const { return px; }
-  operator bool() const { return !expired(); }
+  explicit operator bool() const { return !expired(); }
   void reset() { px = 0; }
 private:
   T     *px;
@@ -448,18 +452,6 @@ destroyMapValues(Container& c) {
   }
 }
 
-// Arbitrary callback when a scope exits.
-struct ScopeGuard {
-  typedef std::tr1::function<void()> Callback;
-
-  ScopeGuard(void(*cbFptr)()) : m_cb(Callback(cbFptr)) { }
-  ScopeGuard(Callback cb) : m_cb(cb) { }
-  ~ScopeGuard() { m_cb(); }
-private:
-  Callback m_cb;
-};
-
-
 
 ///////////////////////////////////////////////////////////////////////////////
 // boost
diff --git a/hphp/util/biased_coin.h b/hphp/util/biased_coin.h
index dd4682075..699c85d14 100644
--- a/hphp/util/biased_coin.h
+++ b/hphp/util/biased_coin.h
@@ -28,7 +28,10 @@ class BiasedCoin {
   unsigned m_state;
 
  public:
-  BiasedCoin(double pct, unsigned seed = -1u) : m_seed(seed), m_pct(pct) {
+  explicit BiasedCoin(double pct, unsigned seed = -1u)
+    : m_seed(seed)
+    , m_pct(pct)
+  {
     assert(pct <= 100.0);
     if (seed == -1u) {
       seed = getpid();
diff --git a/hphp/util/cronoutils.h b/hphp/util/cronoutils.h
index 23e9a75b9..2c1a1fdd8 100644
--- a/hphp/util/cronoutils.h
+++ b/hphp/util/cronoutils.h
@@ -71,7 +71,8 @@
  * NEED_GETOPT_DEFS can be defined and declarations are provided here.
  */
 
-#if !defined(_CRONOUTILS_H_)
+#ifndef incl_HPHP_CRONOUTILS_H_
+#define incl_HPHP_CRONOUTILS_H_
 
 /* Header files */
 
diff --git a/hphp/util/db_conn.h b/hphp/util/db_conn.h
index 001facbd0..8af101e07 100644
--- a/hphp/util/db_conn.h
+++ b/hphp/util/db_conn.h
@@ -110,7 +110,7 @@ class DBConn {
   static unsigned int DefaultReadTimeout;
 
  public:
-  DBConn(int maxRetryOpenOnFail = 0, int maxRetryQueryOnFail = 1);
+  explicit DBConn(int maxRetryOpenOnFail = 0, int maxRetryQueryOnFail = 1);
   ~DBConn();
 
   /**
diff --git a/hphp/util/db_dataset.h b/hphp/util/db_dataset.h
index 6098b92aa..85b5bb12b 100644
--- a/hphp/util/db_dataset.h
+++ b/hphp/util/db_dataset.h
@@ -57,7 +57,8 @@ class DBDataSet : public DataSet {
   virtual int getFieldLength(int field) const;
 
  private:
-  DBDataSet(DBDataSet &ds) { assert(false);} // no copy constructor
+  DBDataSet(const DBDataSet &ds) = delete;
+  DBDataSet& operator=(const DBDataSet&) = delete;
 
   typedef std::list<MYSQL_RES*> ResultList;
   ResultList m_results;
diff --git a/hphp/util/db_filter.h b/hphp/util/db_filter.h
index 8c8c781c3..ab66c7bc5 100644
--- a/hphp/util/db_filter.h
+++ b/hphp/util/db_filter.h
@@ -91,7 +91,7 @@ class DBInStringFilter : public DBQueryFilter {
   /**
    * We need a connection object to escape strings.
    */
-  DBInStringFilter(DBConn *conn);
+  explicit DBInStringFilter(DBConn *conn);
 
   /**
    * Just keep adding strings to the filter.
diff --git a/hphp/util/disasm.cpp b/hphp/util/disasm.cpp
index a6bd4e349..63783a143 100644
--- a/hphp/util/disasm.cpp
+++ b/hphp/util/disasm.cpp
@@ -13,6 +13,7 @@
    | license@php.net so we can mail you a copy immediately.               |
    +----------------------------------------------------------------------+
 */
+#include "util/disasm.h"
 
 #include <iomanip>
 #include <stdlib.h>
@@ -22,7 +23,6 @@
 #include "folly/Format.h"
 #include "folly/ScopeGuard.h"
 
-#include "util/disasm.h"
 #include "util/base.h"
 #include "util/text_color.h"
 
diff --git a/hphp/util/disasm.h b/hphp/util/disasm.h
index c6356d2e1..6f331da2c 100644
--- a/hphp/util/disasm.h
+++ b/hphp/util/disasm.h
@@ -13,7 +13,7 @@
    | license@php.net so we can mail you a copy immediately.               |
    +----------------------------------------------------------------------+
 */
-#ifndef incl_HPHP_UTIL_DISAASM_H_
+#ifndef incl_HPHP_UTIL_DISASM_H_
 #define incl_HPHP_UTIL_DISASM_H_
 
 #ifdef HAVE_LIBXED
diff --git a/hphp/util/embedded_vfs.cpp b/hphp/util/embedded_vfs.cpp
index b4530a939..71ac6e686 100644
--- a/hphp/util/embedded_vfs.cpp
+++ b/hphp/util/embedded_vfs.cpp
@@ -13,6 +13,7 @@
    | license@php.net so we can mail you a copy immediately.               |
    +----------------------------------------------------------------------+
 */
+#include "util/embedded_vfs.h"
 
 /*
  * based on test_demovfs.c and test_multiplex.c in sqlite3
@@ -28,7 +29,6 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 
-#include "embedded_vfs.h"
 
 #ifndef SQLITE_CORE
   #define SQLITE_CORE 1  /* Disable the API redefinition in sqlite3ext.h */
diff --git a/hphp/util/exception.h b/hphp/util/exception.h
index 4c7d073aa..2e4ffda92 100644
--- a/hphp/util/exception.h
+++ b/hphp/util/exception.h
@@ -61,7 +61,7 @@ public:
   struct Deleter {
     Exception* m_e;
     Deleter() : m_e(nullptr) {}
-    Deleter(Exception* e) : m_e(e) {}
+    explicit Deleter(Exception* e) : m_e(e) {}
     ~Deleter() { delete m_e; }
   };
 
@@ -82,7 +82,7 @@ protected:
 
 class FileOpenException : public Exception {
 public:
-  FileOpenException(const char *filename)
+  explicit FileOpenException(const char *filename)
       : Exception("Unable to open file %s", filename) {
   }
 
@@ -95,8 +95,8 @@ class VMSwitchModeException : public Exception {
 private:
   bool m_unwindBuiltin;
 public:
-  VMSwitchModeException(bool m_unwindBuiltin)
-    : m_unwindBuiltin(m_unwindBuiltin) {}
+  explicit VMSwitchModeException(bool unwindBuiltin)
+    : m_unwindBuiltin(unwindBuiltin) {}
   bool unwindBuiltin() const { return m_unwindBuiltin; }
 
   EXCEPTION_COMMON_IMPL(VMSwitchModeException);
diff --git a/hphp/util/hdf.h b/hphp/util/hdf.h
index a41dbcc0b..cac7fc189 100644
--- a/hphp/util/hdf.h
+++ b/hphp/util/hdf.h
@@ -46,12 +46,12 @@ public:
   /**
    * Constructors.
    */
-  Hdf();                                 // create an empty HDF tree
-  Hdf(const char *filename);             // open the specified file
-  Hdf(const std::string &filename);      // open the specified file
-  Hdf(const Hdf *hdf, const char *name); // constructing a sub-node  (internal)
-  Hdf(const Hdf &hdf);                   // make a copy by reference (internal)
-  Hdf(HDF *hdf);                         // attaching a raw pointer  (internal)
+  Hdf();                                          // create an empty HDF tree
+  explicit Hdf(const char *filename);             // open the specified file
+  explicit Hdf(const std::string &filename);      // open the specified file
+  explicit Hdf(const Hdf *hdf, const char *name); // constructing a sub-node
+           Hdf(const Hdf &hdf);                   // make a copy by reference
+  explicit Hdf(HDF *hdf);                         // attaching a raw pointer
   ~Hdf();
 
   /**
@@ -135,19 +135,6 @@ public:
   void get(std::map<std::string, std::string> &values) const;
   void get(hphp_string_imap<std::string> &values) const;
 
-  operator const char *() const { return get();}
-  operator std::string() const { return getString();}
-  operator bool   () const { return getBool()  ;}
-  operator char   () const { return getByte()  ;}
-  operator uchar  () const { return getUByte() ;}
-  operator int16_t  () const { return getInt16() ;}
-  operator uint16_t () const { return getUInt16();}
-  operator int32_t  () const { return getInt32() ;}
-  operator uint32_t () const { return getUInt32();}
-  operator int64_t  () const { return getInt64() ;}
-  operator uint64_t () const { return getUInt64();}
-  operator double () const { return getDouble();}
-
   /**
    * Set this node's value.
    */
@@ -396,7 +383,7 @@ public:
  */
 class HdfDataValueException : public HdfException {
 public:
-  HdfDataValueException(const Hdf *hdf, const char *expected = "")
+  explicit HdfDataValueException(const Hdf *hdf, const char *expected = "")
     : HdfException("HDF node [%s]'s value \"%s\" is not expected %s",
                    hdf->getFullPath().c_str(), hdf->get(""), expected) {
   }
@@ -408,7 +395,7 @@ public:
  */
 class HdfInvalidOperation : public HdfException {
 public:
-  HdfInvalidOperation(const char *operation)
+  explicit HdfInvalidOperation(const char *operation)
     : HdfException("Invalid operation: %s", operation) {
   }
   EXCEPTION_COMMON_IMPL(HdfInvalidOperation);
diff --git a/hphp/util/json.h b/hphp/util/json.h
index 4a2440966..b5b8eb247 100644
--- a/hphp/util/json.h
+++ b/hphp/util/json.h
@@ -55,11 +55,11 @@ public:
 
 class Name {
 public:
-  Name(const char *name) {
+  explicit Name(const char *name) {
     assert(name && *name);
     m_name = name;
   }
-  Name(const std::string &name) {
+  explicit Name(const std::string &name) {
     assert(!name.empty());
     m_name = name;
   }
@@ -193,7 +193,7 @@ private:
 template <typename Type>
 class _MapStream {
 public:
-  _MapStream(_OutputStream<Type> &jout)
+  explicit _MapStream(_OutputStream<Type> &jout)
     : m_out(jout.raw()), m_jout(jout), m_first(true) {}
 
   template<typename T>
@@ -234,7 +234,7 @@ private:
 template <typename Type>
 class _ListStream {
 public:
-  _ListStream(_OutputStream<Type> &jout)
+  explicit _ListStream(_OutputStream<Type> &jout)
     : m_out(jout.raw()), m_jout(jout), m_first(true) {}
 
   void next() {
diff --git a/hphp/util/kernel_version.h b/hphp/util/kernel_version.h
index 81339101c..10ffbd2a7 100644
--- a/hphp/util/kernel_version.h
+++ b/hphp/util/kernel_version.h
@@ -26,7 +26,7 @@ struct KernelVersion {
   int m_dash;
   int m_fbk;
   KernelVersion();             // Use uname
-  KernelVersion(const char*);  // A known kernel version for cmp.
+  explicit KernelVersion(const char*);  // A known kernel version for cmp.
   static int cmp(const KernelVersion& l, const KernelVersion& r) {
 #define C(field) if (l.field != r.field) return l.field - r.field;
     C(m_major);
diff --git a/hphp/util/lock.h b/hphp/util/lock.h
index feaf1b282..2d7919b0f 100644
--- a/hphp/util/lock.h
+++ b/hphp/util/lock.h
@@ -34,7 +34,7 @@ public:
   static bool s_profile;
   static int s_profile_sampling;
 
-  LockProfiler(bool profile);
+  explicit LockProfiler(bool profile);
   ~LockProfiler();
 
 private:
@@ -96,23 +96,23 @@ public:
  */
 class Lock : public ConditionalLock {
 public:
-  Lock(Mutex &mutex, bool profile = true)
+  explicit Lock(Mutex &mutex, bool profile = true)
     : ConditionalLock(mutex, true, profile) {}
-  Lock(Synchronizable *obj, bool profile = true)
+  explicit Lock(Synchronizable *obj, bool profile = true)
     : ConditionalLock(obj, true, profile) {}
-  Lock(SynchronizableMulti *obj, bool profile = true)
+  explicit Lock(SynchronizableMulti *obj, bool profile = true)
     : ConditionalLock(obj, true, profile) {}
 };
 
 class ScopedUnlock {
 public:
-  ScopedUnlock(Mutex &mutex) : m_mutex(mutex) {
+  explicit ScopedUnlock(Mutex &mutex) : m_mutex(mutex) {
     m_mutex.unlock();
   }
-  ScopedUnlock(Synchronizable *obj) : m_mutex(obj->getMutex()) {
+  explicit ScopedUnlock(Synchronizable *obj) : m_mutex(obj->getMutex()) {
     m_mutex.unlock();
   }
-  ScopedUnlock(SynchronizableMulti *obj) : m_mutex(obj->getMutex()) {
+  explicit ScopedUnlock(SynchronizableMulti *obj) : m_mutex(obj->getMutex()) {
     m_mutex.unlock();
   }
 
@@ -138,7 +138,7 @@ public:
 
 class SimpleLock : public SimpleConditionalLock {
 public:
-  SimpleLock(SimpleMutex &mutex, bool profile = true)
+  explicit SimpleLock(SimpleMutex &mutex, bool profile = true)
     : SimpleConditionalLock(mutex, true, profile) {}
 };
 
@@ -169,13 +169,13 @@ private:
 
 class ReadLock : public ConditionalReadLock {
 public:
-  ReadLock(ReadWriteMutex &mutex, bool profile = true)
+  explicit ReadLock(ReadWriteMutex &mutex, bool profile = true)
     : ConditionalReadLock(mutex, true, profile) {}
 };
 
 class WriteLock {
 public:
-  WriteLock(ReadWriteMutex &mutex, bool profile = true)
+  explicit WriteLock(ReadWriteMutex &mutex, bool profile = true)
     : m_profiler(profile), m_mutex(mutex) {
     m_mutex.acquireWrite();
   }
diff --git a/hphp/util/logger.h b/hphp/util/logger.h
index 8cf4f914a..aa8315d9b 100644
--- a/hphp/util/logger.h
+++ b/hphp/util/logger.h
@@ -32,7 +32,11 @@ class Exception;
 class LogFileData {
 public:
   LogFileData() : log(nullptr), bytesWritten(0), prevBytesWritten(0) {}
-  LogFileData(FILE *f) : log(f), bytesWritten(0), prevBytesWritten(0) {}
+  explicit LogFileData(FILE *f)
+    : log(f)
+    , bytesWritten(0)
+    , prevBytesWritten(0)
+  {}
   LogFileData(const LogFileData& rhs) :
       log(rhs.log), prevBytesWritten(rhs.prevBytesWritten) {
     bytesWritten.store(rhs.bytesWritten.load());
diff --git a/hphp/util/maphuge.h b/hphp/util/maphuge.h
index b47e0bf71..71c8384bc 100644
--- a/hphp/util/maphuge.h
+++ b/hphp/util/maphuge.h
@@ -13,6 +13,11 @@
    | license@php.net so we can mail you a copy immediately.               |
    +----------------------------------------------------------------------+
 */
+#ifndef incl_HPHP_MAPHUGE_H_
+#define incl_HPHP_MAPHUGE_H_
+
 namespace HPHP {
 void hintHuge(void* mem, size_t length);
 }
+
+#endif
diff --git a/hphp/util/mutex.h b/hphp/util/mutex.h
index 5f4e58f8c..e3654a7d3 100644
--- a/hphp/util/mutex.h
+++ b/hphp/util/mutex.h
@@ -95,7 +95,7 @@ public:
 #endif
   }
 public:
-  BaseMutex(bool recursive = true, Rank r = RankUnranked) {
+  explicit BaseMutex(bool recursive = true, Rank r = RankUnranked) {
     pthread_mutexattr_init(&m_mutexattr);
     if (recursive) {
       pthread_mutexattr_settype(&m_mutexattr, PTHREAD_MUTEX_RECURSIVE);
@@ -189,7 +189,7 @@ protected:
  */
 class Mutex : public BaseMutex<false> {
 public:
-  Mutex(bool recursive = true, Rank rank = RankUnranked) :
+  explicit Mutex(bool recursive = true, Rank rank = RankUnranked) :
     BaseMutex<false>(recursive, rank) {}
   pthread_mutex_t &getRaw() { return m_mutex; }
 };
@@ -200,7 +200,7 @@ public:
  */
 class SimpleMutex : public BaseMutex<true> {
 public:
-  SimpleMutex(bool recursive = true, Rank rank = RankUnranked) :
+  explicit SimpleMutex(bool recursive = true, Rank rank = RankUnranked) :
     BaseMutex<true>(recursive, rank) {}
 };
 
@@ -211,7 +211,7 @@ class SpinLock {
   Rank m_rank;
 #endif
 public:
-  SpinLock(Rank rank = RankUnranked)
+  explicit SpinLock(Rank rank = RankUnranked)
 #ifdef DEBUG
     : m_rank(rank)
 #endif
@@ -283,7 +283,7 @@ class ReadWriteMutex {
   }
 
 public:
-  ReadWriteMutex(Rank rank = RankUnranked)
+  explicit ReadWriteMutex(Rank rank = RankUnranked)
 #ifdef DEBUG
     : m_rank(rank)
 #endif
diff --git a/hphp/util/repo_schema.h b/hphp/util/repo_schema.h
index 52a6cb690..e3dd3d797 100644
--- a/hphp/util/repo_schema.h
+++ b/hphp/util/repo_schema.h
@@ -13,6 +13,8 @@
    | license@php.net so we can mail you a copy immediately.               |
    +----------------------------------------------------------------------+
 */
+#ifndef incl_HPHP_REPO_SCHEMA_H_
+#define incl_HPHP_REPO_SCHEMA_H_
 
 namespace HPHP {
 
@@ -25,3 +27,5 @@ extern const char* kRepoSchemaId;
 //////////////////////////////////////////////////////////////////////
 
 }
+
+#endif
diff --git a/hphp/util/shared_memory_allocator.h b/hphp/util/shared_memory_allocator.h
index 6a7077704..082ed8e69 100644
--- a/hphp/util/shared_memory_allocator.h
+++ b/hphp/util/shared_memory_allocator.h
@@ -220,7 +220,7 @@ public:
     return boost::interprocess::named_mutex::remove(name);
   }
 
-  SharedMemoryLock(const char *name) {
+  explicit SharedMemoryLock(const char *name) {
     assert(name && *name);
     m_mutex = new boost::interprocess::named_mutex
       (boost::interprocess::open_or_create, name);
diff --git a/hphp/util/shm_counter.h b/hphp/util/shm_counter.h
index 0fde23d2b..f62d9fdc5 100644
--- a/hphp/util/shm_counter.h
+++ b/hphp/util/shm_counter.h
@@ -32,7 +32,7 @@ namespace HPHP {
 class ShmCounter {
 public:
   ShmCounter() {}
-  ShmCounter(const char *n) : count(0) {
+  explicit ShmCounter(const char *n) : count(0) {
     size_t size = sizeof(name);
     strncpy(name, n, size);
     name[size - 1] = '\0';
diff --git a/hphp/util/stack_trace.h b/hphp/util/stack_trace.h
index d332f17ee..893d6fc05 100644
--- a/hphp/util/stack_trace.h
+++ b/hphp/util/stack_trace.h
@@ -31,7 +31,7 @@ public:
   DECLARE_BOOST_TYPES(Frame);
   class Frame {
   public:
-    Frame(void *_bt) : bt(_bt), lineno(0), offset(0) {}
+    explicit Frame(void *_bt) : bt(_bt), lineno(0), offset(0) {}
 
     void *bt;
     int lineno;
@@ -71,7 +71,7 @@ public:
   DECLARE_BOOST_TYPES(Frame);
   class Frame : public StackTraceBase::Frame {
   public:
-    Frame(void *_bt) : StackTraceBase::Frame(_bt) {}
+    explicit Frame(void *_bt) : StackTraceBase::Frame(_bt) {}
     std::string filename;
     std::string funcname;
     std::string toString() const;
@@ -79,7 +79,7 @@ public:
 
 public:
 
-  StackTrace(bool trace = true) ;
+  explicit StackTrace(bool trace = true) ;
 
   /**
    * Translate a frame pointer to file name and line number pair.
@@ -100,9 +100,8 @@ public:
   /**
    * Constructing from hexEncode() results.
    */
-  StackTrace(const std::string &hexEncoded);
-
-  StackTrace(const char *hexEncoded);
+  explicit StackTrace(const std::string &hexEncoded);
+  explicit StackTrace(const char *hexEncoded);
 
   /**
    * Generate an output of the written stack trace.
@@ -138,7 +137,7 @@ public:
    * Constructor, and this will save current stack trace if trace is true.
    * It can be false for an empty stacktrace.
    */
-  StackTraceNoHeap(bool trace = true) ;
+  explicit StackTraceNoHeap(bool trace = true);
 
   /**
    * Log stacktrace into a file under /tmp. If "out" is not null,
diff --git a/hphp/util/string_bag.h b/hphp/util/string_bag.h
index 2c5c61d64..d9be37e91 100644
--- a/hphp/util/string_bag.h
+++ b/hphp/util/string_bag.h
@@ -28,7 +28,7 @@ namespace HPHP {
  */
 class StringBag {
 public:
-  StringBag(int reserve_count = 0);
+  explicit StringBag(int reserve_count = 0);
   ~StringBag();
 
   const char *add(const char *s);
diff --git a/hphp/util/synchronizable.cpp b/hphp/util/synchronizable.cpp
index bed6eeed1..2d6ace280 100644
--- a/hphp/util/synchronizable.cpp
+++ b/hphp/util/synchronizable.cpp
@@ -13,10 +13,10 @@
    | license@php.net so we can mail you a copy immediately.               |
    +----------------------------------------------------------------------+
 */
+#include "util/synchronizable.h"
 
-#include "compatibility.h"
-#include "rank.h"
-#include "synchronizable.h"
+#include "util/compatibility.h"
+#include "util/rank.h"
 
 namespace HPHP {
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/hphp/util/synchronizable_multi.h b/hphp/util/synchronizable_multi.h
index 1cd74542c..d5362266e 100644
--- a/hphp/util/synchronizable_multi.h
+++ b/hphp/util/synchronizable_multi.h
@@ -17,9 +17,9 @@
 #ifndef incl_HPHP_SYNCHRONIZABLE_MULTI_H_
 #define incl_HPHP_SYNCHRONIZABLE_MULTI_H_
 
-#include "base.h"
-#include "mutex.h"
-#include "rank.h"
+#include "util/base.h"
+#include "util/mutex.h"
+#include "util/rank.h"
 
 namespace HPHP {
 ///////////////////////////////////////////////////////////////////////////////
@@ -32,7 +32,7 @@ namespace HPHP {
  */
 class SynchronizableMulti {
 public:
-  SynchronizableMulti(int size);
+  explicit SynchronizableMulti(int size);
   virtual ~SynchronizableMulti();
 
   /**