export

R=r
OCL=16018
CL=16022
diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index 51cf162..c47c016 100644
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -386,6 +386,9 @@
 		// i is in &n1
 		// w is width
 
+		if(w == 0)
+			fatal("index is zero width");
+
 		if(isptrdarray(nl->type)) {
 			regalloc(&n2, types[tptr], res);
 			gmove(res, &n2);