diff --git a/builtin/config.c b/builtin/config.c
index 5677c942b6..fcd8474701 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -395,19 +395,6 @@ static int urlmatch_collect_fn(const char *var, const char *value, void *cb)
 	return 0;
 }
 
-static char *dup_downcase(const char *string)
-{
-	char *result;
-	size_t len, i;
-
-	len = strlen(string);
-	result = xmalloc(len + 1);
-	for (i = 0; i < len; i++)
-		result[i] = tolower(string[i]);
-	result[i] = '\0';
-	return result;
-}
-
 static int get_urlmatch(const char *var, const char *url)
 {
 	char *section_tail;
@@ -422,7 +409,7 @@ static int get_urlmatch(const char *var, const char *url)
 	if (!url_normalize(url, &config.url))
 		die("%s", config.url.err);
 
-	config.section = dup_downcase(var);
+	config.section = xstrdup_tolower(var);
 	section_tail = strchr(config.section, '.');
 	if (section_tail) {
 		*section_tail = '\0';
diff --git a/daemon.c b/daemon.c
index eba1255684..f9c63e9613 100644
--- a/daemon.c
+++ b/daemon.c
@@ -475,14 +475,6 @@ static void make_service_overridable(const char *name, int ena)
 	die("No such service %s", name);
 }
 
-static char *xstrdup_tolower(const char *str)
-{
-	char *p, *dup = xstrdup(str);
-	for (p = dup; *p; p++)
-		*p = tolower(*p);
-	return dup;
-}
-
 static void parse_host_and_port(char *hostport, char **host,
 	char **port)
 {
diff --git a/strbuf.c b/strbuf.c
index 4d31567a1a..f5d609a51f 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -563,3 +563,16 @@ int fprintf_ln(FILE *fp, const char *fmt, ...)
 		return -1;
 	return ret + 1;
 }
+
+char *xstrdup_tolower(const char *string)
+{
+	char *result;
+	size_t len, i;
+
+	len = strlen(string);
+	result = xmalloc(len + 1);
+	for (i = 0; i < len; i++)
+		result[i] = tolower(string[i]);
+	result[i] = '\0';
+	return result;
+}
diff --git a/strbuf.h b/strbuf.h
index 39c14cfa38..4de7531c43 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -183,4 +183,6 @@ extern int printf_ln(const char *fmt, ...);
 __attribute__((format (printf,2,3)))
 extern int fprintf_ln(FILE *fp, const char *fmt, ...);
 
+char *xstrdup_tolower(const char *);
+
 #endif /* STRBUF_H */