diff --git a/usr.bin/rpcgen/rpc_main.c b/usr.bin/rpcgen/rpc_main.c
index 35a0f71cc725..7fbc8b8198d8 100644
--- a/usr.bin/rpcgen/rpc_main.c
+++ b/usr.bin/rpcgen/rpc_main.c
@@ -874,7 +874,7 @@ struct commandline *cmd;
 		mkfilename = xmalloc(strlen("makefile.") +
 		                     strlen(cmd->infile) + 1);
 		temp = (char *)rindex(cmd->infile, '.');
-		strcat(mkfilename, "makefile.");
+		strcpy(mkfilename, "makefile.");
 		(void) strncat(mkfilename, cmd->infile,
 			(temp - cmd->infile));
 	} else