--- src\emu\inptport.c	2008-06-05 12:23:40.000000000 -0400
+++ update\inptport.c	2008-06-05 13:54:32.000000000 -0400
@@ -731,6 +731,8 @@
 
 const input_port_config *input_port_config_alloc(const input_port_token *tokens, char *errorbuf, int errorbuflen)
 {
+        if (tokens == NULL)
+                 return NULL;
 	if (errorbuf != NULL)
 		*errorbuf = 0;
 	return port_config_detokenize(NULL, tokens, errorbuf, errorbuflen);