diff --git a/src/client/mac/sender/uploader.mm b/src/client/mac/sender/uploader.mm
index 7298ed42..b876b9e2 100644
--- a/src/client/mac/sender/uploader.mm
+++ b/src/client/mac/sender/uploader.mm
@@ -251,7 +251,7 @@ NSDictionary *readConfigurationData(const char *configFile) {
   long clientId1 = random();
   long clientId2 = random();
   long clientId3 = random();
-  crashClientID = [NSString stringWithFormat:@"%x%x%x",
+  crashClientID = [NSString stringWithFormat:@"%lx%lx%lx",
                             clientId1, clientId2, clientId3];
 
   [ud setObject:crashClientID forKey:kClientIdPreferenceKey];