diff --git a/Documentation/perf_counter/builtin-top.c b/Documentation/perf_counter/builtin-top.c
index cd6f61d734181c4f7403f655e6d9a89f553dbfb1..b1549dd27720081f0c3638d2b3d5bafbae6164ac 100644
--- a/Documentation/perf_counter/builtin-top.c
+++ b/Documentation/perf_counter/builtin-top.c
@@ -523,7 +523,7 @@ static int read_symbol(FILE *in, struct sym_entry *s)
 	if (strstr(sym, "_text_start") || strstr(sym, "_text_end"))
 		return 1;
 
-	s->sym = malloc(strlen(str));
+	s->sym = malloc(strlen(str)+1);
 	assert(s->sym);
 
 	strcpy((char *)s->sym, str);