--- a/src/cmd/tpc.t
+++ b/src/cmd/tpc.t
@@ -1342,6 +1342,10 @@ procedure CompileC (cFileName : string, var s : string, var status : int)
 	i += 1
     end if
 
+    % Use C standard that allows C++-style comments
+    tArgs(i) := "-std=gnu89"
+    i += 1
+
     % ignore warnings from C compiler 
     tArgs(i) := "-w"
     i += 1