diff --git a/tools/perf/util/string.h b/tools/perf/util/string.h
index 15c82747..2c84bf6 100644
--- a/tools/perf/util/string.h
+++ b/tools/perf/util/string.h
@@ -4,6 +4,7 @@
 #include "types.h"
 
 int hex2u64(const char *ptr, u64 *val);
+char *strxfrchar(char *s, char from, char to);
 
 #define _STR(x) #x
 #define STR(x) _STR(x)