--- a/dom/url/URLSearchParams.cpp
+++ b/dom/url/URLSearchParams.cpp
@@ -93,25 +93,25 @@ URLParams::Delete(const nsAString& aName
     if (mParams[i].mKey.Equals(aName)) {
       mParams.RemoveElementAt(i);
     } else {
       ++i;
     }
   }
 }
 
-void
+/* static */ void
 URLParams::ConvertString(const nsACString& aInput, nsAString& aOutput)
 {
   if (NS_FAILED(UTF_8_ENCODING->DecodeWithoutBOMHandling(aInput, aOutput))) {
     MOZ_CRASH("Out of memory when converting URL params.");
   }
 }
 
-void
+/* static */ void
 URLParams::DecodeString(const nsACString& aInput, nsAString& aOutput)
 {
   nsACString::const_iterator start, end;
   aInput.BeginReading(start);
   aInput.EndReading(end);
 
   nsCString unescaped;
 

--- a/dom/url/URLSearchParams.h
+++ b/dom/url/URLSearchParams.h
@@ -108,18 +108,18 @@ public:
 
   bool
   ReadStructuredClone(JSStructuredCloneReader* aReader);
 
   bool
   WriteStructuredClone(JSStructuredCloneWriter* aWriter) const;
 
 private:
-  void DecodeString(const nsACString& aInput, nsAString& aOutput);
-  void ConvertString(const nsACString& aInput, nsAString& aOutput);
+  static void DecodeString(const nsACString& aInput, nsAString& aOutput);
+  static void ConvertString(const nsACString& aInput, nsAString& aOutput);
 
   struct Param
   {
     nsString mKey;
     nsString mValue;
   };
 
   nsTArray<Param> mParams;