diff --git a/dom/canvas/WebGLSampler.h b/dom/canvas/WebGLSampler.h
index d3d6a9b37f26..f87c4728f8d9 100644
--- a/dom/canvas/WebGLSampler.h
+++ b/dom/canvas/WebGLSampler.h
@@ -26,7 +26,7 @@ class WebGLSampler MOZ_FINAL
 
 public:
 
-    WebGLSampler(WebGLContext* context);
+    explicit WebGLSampler(WebGLContext* aContext);
 
     void Delete();
     WebGLContext* GetParentObject() const;
diff --git a/dom/canvas/WebGLStrongTypes.h b/dom/canvas/WebGLStrongTypes.h
index 0ca7c8227c2a..775f2e875f91 100644
--- a/dom/canvas/WebGLStrongTypes.h
+++ b/dom/canvas/WebGLStrongTypes.h
@@ -8,8 +8,9 @@
 #define WEBGLSTRONGTYPES_H_
 
 #include "GLDefs.h"
-#include "mozilla/Assertions.h"
 #include "mozilla/ArrayUtils.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
 
 // Usage:
 // ===========
@@ -132,8 +133,8 @@ public:
         AssertOnceThatEnumValuesAreSorted();
     }
 
-    StrongGLenum(GLenum val)
-        : mValue(val)
+    MOZ_IMPLICIT StrongGLenum(GLenum aVal)
+        : mValue(aVal)
     {
         AssertOnceThatEnumValuesAreSorted();
         MOZ_ASSERT(IsValueLegal(mValue));
diff --git a/dom/canvas/WebGLSync.h b/dom/canvas/WebGLSync.h
index 3204646f67ad..54b41faf8527 100644
--- a/dom/canvas/WebGLSync.h
+++ b/dom/canvas/WebGLSync.h
@@ -24,7 +24,7 @@ class WebGLSync MOZ_FINAL
 
 public:
 
-    WebGLSync(WebGLContext* context);
+    explicit WebGLSync(WebGLContext* aContext);
 
     void Delete();
     WebGLContext* GetParentObject() const;
diff --git a/dom/canvas/WebGLTransformFeedback.h b/dom/canvas/WebGLTransformFeedback.h
index 17467c568757..302df01dd922 100644
--- a/dom/canvas/WebGLTransformFeedback.h
+++ b/dom/canvas/WebGLTransformFeedback.h
@@ -26,7 +26,7 @@ class WebGLTransformFeedback MOZ_FINAL
 
 public:
 
-    WebGLTransformFeedback(WebGLContext* context);
+    explicit WebGLTransformFeedback(WebGLContext* aContext);
 
     void Delete();
     WebGLContext* GetParentObject() const;
diff --git a/dom/mobileconnection/ipc/MobileConnectionChild.h b/dom/mobileconnection/ipc/MobileConnectionChild.h
index e31fc2662a5c..062c48106511 100644
--- a/dom/mobileconnection/ipc/MobileConnectionChild.h
+++ b/dom/mobileconnection/ipc/MobileConnectionChild.h
@@ -32,7 +32,7 @@ public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIMOBILECONNECTION
 
-  MobileConnectionChild(uint32_t aServiceId);
+  explicit MobileConnectionChild(uint32_t aServiceId);
 
   void
   Init();