diff --git a/src/cmd/yacc/yacc.go b/src/cmd/yacc/yacc.go
index 6f67ab65669..8a5df052ecf 100644
--- a/src/cmd/yacc/yacc.go
+++ b/src/cmd/yacc/yacc.go
@@ -683,6 +683,10 @@ outer:
 		levprd[nprod] = 0
 	}
 
+	if TEMPSIZE < ntokens+nnonter+1 {
+		errorf("too many tokens (%d) or non-terminals (%d)", ntokens, nnonter)
+	}
+
 	//
 	// end of all rules
 	// dump out the prefix code