diff --git a/darkhttpd.c b/darkhttpd.c
index 05a0daa..c6a1a02 100644
--- a/darkhttpd.c
+++ b/darkhttpd.c
@@ -1600,7 +1600,7 @@ static void redirect(struct connection *conn, const char *format, ...) {
 
 /* Parses a single HTTP request field.  Returns string from end of [field] to
  * first \r, \n or end of request string.  Returns NULL if [field] can't be
- * matched.
+ * matched.  Case insensitive.
  *
  * You need to remember to deallocate the result.
  * example: parse_field(conn, "Referer: ");
@@ -1610,7 +1610,7 @@ static char *parse_field(const struct connection *conn, const char *field) {
     char *pos;
 
     /* find start */
-    pos = strstr(conn->request, field);
+    pos = strcasestr(conn->request, field);
     if (pos == NULL)
         return NULL;
     assert(pos >= conn->request);
diff --git a/devel/test.py b/devel/test.py
index 8b35873..7835c0c 100755
--- a/devel/test.py
+++ b/devel/test.py
@@ -385,6 +385,11 @@ class TestFileGet(TestHelper):
         status, hdrs, body = parse(resp)
         self.assertContains(status, "416 Requested Range Not Satisfiable")
 
+    def test_lowercase_header(self):
+        resp = self.get(self.url, req_hdrs = {"range": "bytes=20-10"})
+        status, hdrs, body = parse(resp)
+        self.assertContains(status, "416 Requested Range Not Satisfiable")
+
 class TestKeepAlive(TestFileGet):
     """
     Run all of TestFileGet but with a single long-lived connection.