diff --git a/flashrom.c b/flashrom.c
index 4fc8fca..b45ac13 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -29,6 +29,7 @@
 #endif
 #include <string.h>
 #include <stdlib.h>
+#include <ctype.h>
 #include <getopt.h>
 #if HAVE_UTSNAME == 1
 #include <sys/utsname.h>
@@ -615,6 +616,12 @@
 	return i;
 }
 
+void tolower_string(char *str)
+{
+	for (; *str != '\0'; str++)
+		*str = (char)tolower((unsigned char)*str);
+}
+
 char *strcat_realloc(char *dest, const char *src)
 {
 	dest = realloc(dest, strlen(dest) + strlen(src) + 1);