diff --git a/tools/widl/parser.y b/tools/widl/parser.y
index 8ca08cd7a0f..0ae032a991b 100644
--- a/tools/widl/parser.y
+++ b/tools/widl/parser.y
@@ -563,6 +563,7 @@ base_type: tBYTE				{ $$ = make_type(RPC_FC_BYTE, NULL); }
 						  default: break;
 						  }
 						}
+	| tUNSIGNED				{ $$ = make_type(RPC_FC_ULONG, &std_int); $$->sign = -1; }
 	| tFLOAT				{ $$ = make_type(RPC_FC_FLOAT, NULL); }
 	| tDOUBLE				{ $$ = make_type(RPC_FC_DOUBLE, NULL); }
 	| tBOOLEAN				{ $$ = make_type(RPC_FC_BYTE, &std_bool); /* ? */ }