diff --git a/editor/txtsvc/src/nsTextServicesDocument.cpp b/editor/txtsvc/src/nsTextServicesDocument.cpp
index 1f08e82380f..b7d41769389 100644
--- a/editor/txtsvc/src/nsTextServicesDocument.cpp
+++ b/editor/txtsvc/src/nsTextServicesDocument.cpp
@@ -80,8 +80,6 @@ public:
 
 nsTextServicesDocument::nsTextServicesDocument()
 {
-  mRefCnt         = 0;
-
   mSelStartIndex  = -1;
   mSelStartOffset = -1;
   mSelEndIndex    = -1;
diff --git a/xpcom/glue/nsISupportsImpl.h b/xpcom/glue/nsISupportsImpl.h
index a773065f428..6cc2a513246 100644
--- a/xpcom/glue/nsISupportsImpl.h
+++ b/xpcom/glue/nsISupportsImpl.h
@@ -138,7 +138,7 @@ public:
     : mRefCntAndFlags(0)
   {}
 
-  nsCycleCollectingAutoRefCnt(uintptr_t aValue)
+  explicit nsCycleCollectingAutoRefCnt(uintptr_t aValue)
     : mRefCntAndFlags(aValue << NS_NUMBER_OF_FLAGS_IN_REFCNT)
   {
   }
@@ -233,7 +233,7 @@ class nsAutoRefCnt {
 
  public:
     nsAutoRefCnt() : mValue(0) {}
-    nsAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
+    explicit nsAutoRefCnt(nsrefcnt aValue) : mValue(aValue) {}
 
     // only support prefix increment/decrement
     nsrefcnt operator++() { return ++mValue; }
diff --git a/xpcom/glue/nsTArray.h b/xpcom/glue/nsTArray.h
index 2bafb97ee46..6906f37a67c 100644
--- a/xpcom/glue/nsTArray.h
+++ b/xpcom/glue/nsTArray.h
@@ -102,7 +102,7 @@ class nsIntRegion;
 struct nsTArrayFallibleResult
 {
   // Note: allows implicit conversions from and to bool
-  nsTArrayFallibleResult(bool result)
+  MOZ_IMPLICIT nsTArrayFallibleResult(bool result)
     : mResult(result)
   {}
 
diff --git a/xpcom/string/public/nsString.h b/xpcom/string/public/nsString.h
index db5cc339c5d..c5e7fc927b7 100644
--- a/xpcom/string/public/nsString.h
+++ b/xpcom/string/public/nsString.h
@@ -83,7 +83,7 @@ public:
 
 private:
   // NOT TO BE IMPLEMENTED
-  NS_LossyConvertUTF16toASCII( char );
+  NS_LossyConvertUTF16toASCII( char ) MOZ_DELETE;
 };
 
 
@@ -109,7 +109,7 @@ public:
 
 private:
   // NOT TO BE IMPLEMENTED
-  NS_ConvertASCIItoUTF16( char16_t );
+  NS_ConvertASCIItoUTF16( char16_t ) MOZ_DELETE;
 };
 
 
@@ -145,7 +145,7 @@ public:
 
 private:
   // NOT TO BE IMPLEMENTED
-  NS_ConvertUTF16toUTF8( char );
+  NS_ConvertUTF16toUTF8( char ) MOZ_DELETE;
 };
 
 
@@ -171,7 +171,7 @@ public:
 
 private:
   // NOT TO BE IMPLEMENTED
-  NS_ConvertUTF8toUTF16( char16_t );
+  NS_ConvertUTF8toUTF16( char16_t ) MOZ_DELETE;
 };
 
 
diff --git a/xpcom/string/public/nsTDependentString.h b/xpcom/string/public/nsTDependentString.h
index 9bd7ed9539b..a554a667d14 100644
--- a/xpcom/string/public/nsTDependentString.h
+++ b/xpcom/string/public/nsTDependentString.h
@@ -94,5 +94,5 @@ public:
 private:
 
   // NOT USED
-  nsTDependentString_CharT( const substring_tuple_type& );
+  nsTDependentString_CharT( const substring_tuple_type& ) MOZ_DELETE;
 };