diff --git a/include/lib/util_libc.h b/include/lib/util_libc.h
index 6b77876e..e5e2f982 100644
--- a/include/lib/util_libc.h
+++ b/include/lib/util_libc.h
@@ -129,6 +129,7 @@ int __util_vsprintf(const char *func, const char *file, int line,
 char *util_strcat_realloc(char *str1, const char *str2);
 void util_concatf(char **str1, const char *fmt, ...);
 void util_str_toupper(char *str);
+void util_str_tolower(char *str);
 
 char *util_strstrip(char *s);
 size_t util_strlcpy(char *dest, const char *src, size_t size);
diff --git a/libutil/util_libc.c b/libutil/util_libc.c
index 8ffd1116..00b33ee3 100644
--- a/libutil/util_libc.c
+++ b/libutil/util_libc.c
@@ -174,6 +174,21 @@ void util_str_toupper(char *str)
 		str[i] = toupper(str[i]);
 }
 
+/**
+ * Convert string to lowercase
+ *
+ * String \a str is converted to lowercase
+ *
+ * @param[in,out] str String to convert
+ */
+void util_str_tolower(char *str)
+{
+	int i;
+
+	for (i = 0; str[i] != '\0'; i++)
+		str[i] = tolower(str[i]);
+}
+
 /*
  * Print to newly allocated string or exit in case of failure
  */