diff --git a/src/cmd/plumb/fsys.c b/src/cmd/plumb/fsys.c
index 0f5bcc8..0ffd505 100644
--- a/src/cmd/plumb/fsys.c
+++ b/src/cmd/plumb/fsys.c
@@ -233,7 +233,7 @@
 			error("convert error in convM2S");
 		if(debug)
 			fprint(2, "<= %F\n", t);
-		if(fcall[t->type] == nil)
+		if(fcall[t->type] == 0)
 			fsysrespond(t, buf, Ebadfcall);
 		else{
 			if(t->type==Tversion || t->type==Tauth)