diff --git a/content/base/public/nsIDocument.h b/content/base/public/nsIDocument.h
index 2a176b85722..e38e3564824 100644
--- a/content/base/public/nsIDocument.h
+++ b/content/base/public/nsIDocument.h
@@ -1579,7 +1579,7 @@ public:
   void WarnOnceAbout(DeprecatedOperations aOperation);
 
 private:
-  PRUint32 mWarnedAbout;
+  PRUint64 mWarnedAbout;
 
 protected:
   ~nsIDocument()
diff --git a/content/base/src/nsDocument.cpp b/content/base/src/nsDocument.cpp
index 73e2cfdb0e3..a4194e01974 100644
--- a/content/base/src/nsDocument.cpp
+++ b/content/base/src/nsDocument.cpp
@@ -8156,7 +8156,7 @@ static const char* kWarnings[] = {
 void
 nsIDocument::WarnOnceAbout(DeprecatedOperations aOperation)
 {
-  PR_STATIC_ASSERT(eDeprecatedOperationCount <= 32);
+  PR_STATIC_ASSERT(eDeprecatedOperationCount <= 64);
   if (mWarnedAbout & (1 << aOperation)) {
     return;
   }