diff --git a/lib/Makefile b/lib/Makefile
index e290fc5707ea..a4a4c6864f51 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -15,11 +15,16 @@ KCOV_INSTRUMENT_debugobjects.o := n
 KCOV_INSTRUMENT_dynamic_debug.o := n
 KCOV_INSTRUMENT_fault-inject.o := n
 
+# string.o implements standard library functions like memset/memcpy etc.
+# Use -ffreestanding to ensure that the compiler does not try to "optimize"
+# them into calls to themselves.
+CFLAGS_string.o := -ffreestanding
+
 # Early boot use of cmdline, don't instrument it
 ifdef CONFIG_AMD_MEM_ENCRYPT
 KASAN_SANITIZE_string.o := n
 
-CFLAGS_string.o := -fno-stack-protector
+CFLAGS_string.o += -fno-stack-protector
 endif
 
 # Used by KCSAN while enabled, avoid recursion.