--- a/netwerk/protocol/http/nsHttpHandler.cpp
+++ b/netwerk/protocol/http/nsHttpHandler.cpp
@@ -341,17 +341,17 @@ nsHttpHandler::SetFastOpenOSSupport()
     }
 #endif
 
     LOG(("nsHttpHandler::SetFastOpenOSSupport version %s", version.get()));
 
     if (NS_SUCCEEDED(rv)) {
         // set min version minus 1.
 #if XP_MACOSX
-        int min_version[] = {17, 3};
+        int min_version[] = {17, 4}; // High Sierra 10.13.4
 #elif ANDROID
         int min_version[] = {4, 4};
 #elif XP_LINUX
         int min_version[] = {3, 6};
 #endif
         int inx = 0;
         nsCCharSeparatedTokenizer tokenizer(version, '.');
         while ((inx < 2) && tokenizer.hasMoreTokens()) {