Index: cups/ppd.c
===================================================================
--- cups/ppd.c	(revision 9306)
+++ cups/ppd.c	(working copy)
@@ -663,6 +663,8 @@
 
       goto error;
     }
+    else if (!string)
+      continue;
 
    /*
     * Certain main keywords (as defined by the PPD spec) may be used