diff --git a/config.c b/config.c
index d969a5aefc..314d8ee740 100644
--- a/config.c
+++ b/config.c
@@ -84,8 +84,12 @@ static int handle_path_include(const char *path, struct config_include_data *inc
 {
 	int ret = 0;
 	struct strbuf buf = STRBUF_INIT;
-	char *expanded = expand_user_path(path);
+	char *expanded;
 
+	if (!path)
+		return config_error_nonbool("include.path");
+
+	expanded = expand_user_path(path);
 	if (!expanded)
 		return error("Could not expand include path '%s'", path);
 	path = expanded;
diff --git a/path.c b/path.c
index 24594c4112..f9c5062427 100644
--- a/path.c
+++ b/path.c
@@ -265,12 +265,12 @@ static struct passwd *getpw_str(const char *username, size_t len)
 char *expand_user_path(const char *path)
 {
 	struct strbuf user_path = STRBUF_INIT;
-	const char *first_slash = strchrnul(path, '/');
 	const char *to_copy = path;
 
 	if (path == NULL)
 		goto return_null;
 	if (path[0] == '~') {
+		const char *first_slash = strchrnul(path, '/');
 		const char *username = path + 1;
 		size_t username_len = first_slash - username;
 		if (username_len == 0) {