--- a/webapprt/mac/webapprt.mm
+++ b/webapprt/mac/webapprt.mm
@@ -163,20 +163,28 @@ main(int argc, char **argv)
 
       NSFileManager* fileClerk = [[NSFileManager alloc] init];
       NSError *errorDesc = nil;
 
       //we know the firefox path, so copy the new webapprt here
       NSString *newWebRTPath =
         [NSString stringWithFormat: @"%@%s%s", firefoxPath, APP_RESOURCES_PATH,
                                                WEBAPPRT_EXECUTABLE];
-      NSLog(@"### Firefox webapprt path: %@", newWebRTPath);
+      NSLog(@"### Trying Firefox webapprt path: %@", newWebRTPath);
       if (![fileClerk fileExistsAtPath:newWebRTPath]) {
-        NSString* msg = [NSString stringWithFormat: @"This version of Firefox (%@) cannot run web applications, because it is not recent enough or damaged", firefoxVersion];
-        @throw MakeException(@"Missing Web Runtime Files", msg);
+        newWebRTPath =
+          [NSString stringWithFormat: @"%@%s%s", firefoxPath, APP_MACOS_PATH,
+                                                 WEBAPPRT_EXECUTABLE];
+        NSLog(@"### Trying Firefox webapprt path: %@", newWebRTPath);
+        if (![fileClerk fileExistsAtPath:newWebRTPath]) {
+          NSString* msg =
+            [NSString stringWithFormat:
+              @"This version of Firefox (%@) cannot run web applications, because it is not recent enough or damaged", firefoxVersion];
+          @throw MakeException(@"Missing Web Runtime Files", msg);
+        }
       }
 
       [fileClerk removeItemAtPath: myWebRTPath error: &errorDesc];
       if (errorDesc != nil) {
         NSLog(@"failed to unlink old binary file at path: %@ with error: %@", myWebRTPath, errorDesc);
         @throw MakeException(@"Unable To Update", @"Failed preparation for Web Runtime update");
       }