diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 15fbba9f4ca8..333ddd0e4bd8 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -349,6 +349,7 @@ CORE_CFLAGS += -fno-omit-frame-pointer
 CORE_CFLAGS += -Wall
 CORE_CFLAGS += -Wextra
 CORE_CFLAGS += -std=gnu11
+CORE_CFLAGS += -funsigned-char
 
 CXXFLAGS += -std=gnu++17 -fno-exceptions -fno-rtti
 CXXFLAGS += -Wall