--- a/netwerk/base/nsIOService.cpp
+++ b/netwerk/base/nsIOService.cpp
@@ -517,18 +517,18 @@ UsesExternalProtocolHandler(const char* 
         NS_LITERAL_CSTRING("chrome").Equals(aScheme) ||
         NS_LITERAL_CSTRING("resource").Equals(aScheme)) {
         // Don't allow file:, chrome: or resource: URIs to be handled with
         // nsExternalProtocolHandler, since internally we rely on being able to
         // use and read from these URIs.
         return false;
     }
 
-    for (unsigned int i = 0; i < NS_N(gForcedExternalSchemes); i++) {
-      if (!nsCRT::strcasecmp(gForcedExternalSchemes[i], aScheme)) {
+    for (const auto & forcedExternalScheme : gForcedExternalSchemes) {
+      if (!nsCRT::strcasecmp(forcedExternalScheme, aScheme)) {
         return true;
       }
     }
 
     nsAutoCString pref("network.protocol-handler.external.");
     pref += aScheme;
 
     return Preferences::GetBool(pref.get(), false);