diff --git a/makepanda/makepanda.py b/makepanda/makepanda.py
index fb703e9e52..56720ca314 100755
--- a/makepanda/makepanda.py
+++ b/makepanda/makepanda.py
@@ -245,7 +245,7 @@ def parseopts(args):
         if (len(OSXTARGET) != 4 or not OSXTARGET.startswith("10.")):
             usage("Invalid setting for OSXTARGET")
         try:
-            OSXTARGET = "10.%d" % (OSXTARGET[-1])
+            OSXTARGET = "10.%d" % (str(OSXTARGET[-1]))
         except:
             usage("Invalid setting for OSXTARGET")
     try: