diff --git a/tests/unit/plugins/relay/test-relay-http.cpp b/tests/unit/plugins/relay/test-relay-http.cpp
index 72f816b92..dd5ad8745 100644
--- a/tests/unit/plugins/relay/test-relay-http.cpp
+++ b/tests/unit/plugins/relay/test-relay-http.cpp
@@ -538,6 +538,24 @@ TEST(RelayHttp, ParseHeader)
     CHECK(hashtable_has_key (request->accept_encoding, "br"));
     relay_http_request_free (request);
 
+    request = relay_http_request_alloc ();
+    CHECK(request);
+    relay_http_parse_method_path (request, "GET /api/version");
+    relay_http_parse_header (request, "Accept-Encoding: gzip", 1);
+    relay_http_parse_header (request, "Accept-Encoding: zstd", 1);
+    LONGS_EQUAL(RELAY_HTTP_HEADERS, request->status);
+    STRCMP_EQUAL("GET /api/version\n"
+                 "Accept-Encoding: gzip\n"
+                 "Accept-Encoding: zstd\n",
+                 *(request->raw));
+    LONGS_EQUAL(1, request->headers->items_count);
+    STRCMP_EQUAL("gzip, zstd",
+                 (const char *)hashtable_get (request->headers, "accept-encoding"));
+    LONGS_EQUAL(2, request->accept_encoding->items_count);
+    CHECK(hashtable_has_key (request->accept_encoding, "gzip"));
+    CHECK(hashtable_has_key (request->accept_encoding, "zstd"));
+    relay_http_request_free (request);
+
     request = relay_http_request_alloc ();
     CHECK(request);
     relay_http_parse_method_path (request, "GET /api/version");