diff --git a/src/libgit2/refs.c b/src/libgit2/refs.c
index e01278521..fd0c292ff 100644
--- a/src/libgit2/refs.c
+++ b/src/libgit2/refs.c
@@ -819,7 +819,7 @@ int git_reference_list(
 
 static int is_valid_ref_char(char ch)
 {
-	if ((unsigned) ch <= ' ')
+	if ((unsigned) ch <= ' ' || ch == '\177') /* ASCII control characters */
 		return 0;
 
 	switch (ch) {
diff --git a/tests/libgit2/refs/isvalidname.c b/tests/libgit2/refs/isvalidname.c
index 063f0f798..2e20c67bd 100644
--- a/tests/libgit2/refs/isvalidname.c
+++ b/tests/libgit2/refs/isvalidname.c
@@ -21,6 +21,7 @@ void test_refs_isvalidname__can_detect_invalid_formats(void)
 	cl_assert_equal_i(false, is_valid_name("/"));
 	cl_assert_equal_i(false, is_valid_name("//"));
 	cl_assert_equal_i(false, is_valid_name(""));
+	cl_assert_equal_i(false, is_valid_name("refs/heads/\177"));
 	cl_assert_equal_i(false, is_valid_name("refs/heads/sub.lock/webmatrix"));
 }