--- a/xpcom/ds/nsIAtom.idl
+++ b/xpcom/ds/nsIAtom.idl
@@ -49,17 +49,17 @@ interface nsIAtom : nsISupports
   inline char16ptr_t GetUTF16String() const {
     return mString;
   }
 
   inline uint32_t GetLength() const {
     return mLength;
   }
 
-  inline void ToString(nsAString& aBuf) {
+  inline void ToString(nsAString& aBuf) const {
     // See the comment on |mString|'s declaration.
     nsStringBuffer::FromData(mString)->ToString(mLength, aBuf);
   }
 
   inline nsStringBuffer* GetStringBuffer() const {
     // See the comment on |mString|'s declaration.
     return nsStringBuffer::FromData(mString);
   }
@@ -134,17 +134,17 @@ extern nsIAtom* NS_GetStaticAtom(const n
 /**
  * Seal the static atom table
  */
 extern void NS_SealStaticAtomTable();
 
 class nsAtomString : public nsString
 {
 public:
-  explicit nsAtomString(nsIAtom* aAtom)
+  explicit nsAtomString(const nsIAtom* aAtom)
   {
     aAtom->ToString(*this);
   }
 };
 
 class nsAtomCString : public nsCString
 {
 public:
@@ -152,15 +152,15 @@ public:
   {
     aAtom->ToUTF8String(*this);
   }
 };
 
 class nsDependentAtomString : public nsDependentString
 {
 public:
-  explicit nsDependentAtomString(nsIAtom* aAtom)
+  explicit nsDependentAtomString(const nsIAtom* aAtom)
     : nsDependentString(aAtom->GetUTF16String(), aAtom->GetLength())
   {
   }
 };
 
 %}