diff --git a/hphp/compiler/analysis/emitter.cpp b/hphp/compiler/analysis/emitter.cpp
index 7dd284a63..f6652e4e7 100644
--- a/hphp/compiler/analysis/emitter.cpp
+++ b/hphp/compiler/analysis/emitter.cpp
@@ -1432,7 +1432,7 @@ private:
  */
 class RestoreErrorReportingThunklet : public Thunklet {
 public:
-  RestoreErrorReportingThunklet(Id loc) : m_oldLevelLoc(loc) {}
+  explicit RestoreErrorReportingThunklet(Id loc) : m_oldLevelLoc(loc) {}
   virtual void emit(Emitter& e) {
     e.getEmitterVisitor().emitRestoreErrorReporting(e, m_oldLevelLoc);
     e.Unwind();
@@ -1443,7 +1443,7 @@ private:
 
 class UnsetUnnamedLocalThunklet : public Thunklet {
 public:
-  UnsetUnnamedLocalThunklet(Id loc) : m_loc(loc) {}
+  explicit UnsetUnnamedLocalThunklet(Id loc) : m_loc(loc) {}
   virtual void emit(Emitter& e) {
     e.getEmitterVisitor().emitVirtualLocal(m_loc);
     e.getEmitterVisitor().emitUnset(e);
diff --git a/hphp/compiler/analysis/emitter.h b/hphp/compiler/analysis/emitter.h
index f8963f76f..2c7ae15f4 100644
--- a/hphp/compiler/analysis/emitter.h
+++ b/hphp/compiler/analysis/emitter.h
@@ -287,7 +287,7 @@ public:
 class Label {
 public:
   Label() : m_off(InvalidAbsoluteOffset) {}
-  Label(Emitter& e) : m_off(InvalidAbsoluteOffset) {
+  explicit Label(Emitter& e) : m_off(InvalidAbsoluteOffset) {
     set(e);
   }
   Offset getAbsoluteOffset() const { return m_off; }
@@ -326,7 +326,7 @@ public:
 class EmitterVisitor {
   friend class UnsetUnnamedLocalThunklet;
 public:
-  EmitterVisitor(UnitEmitter& ue);
+  explicit EmitterVisitor(UnitEmitter& ue);
   ~EmitterVisitor();
 
   bool visit(ConstructPtr c);