diff --git a/src/json-validator.cpp b/src/json-validator.cpp
index b06e672..75f5bd8 100644
--- a/src/json-validator.cpp
+++ b/src/json-validator.cpp
@@ -226,10 +226,10 @@ class root_schema
 			// for each token create an object, if not already existing
 			auto unk_kw = &file.unknown_keywords;
 			for (auto &rt : ref_tokens) {
-				auto existing_object = unk_kw->find(rt);
-				if (existing_object == unk_kw->end())
+				json::json_pointer rt_ptr{"/" + rt};
+				if (unk_kw->contains(rt_ptr) == false)
 					(*unk_kw)[rt] = json::object();
-				unk_kw = &(*unk_kw)[rt];
+				unk_kw = &(*unk_kw)[rt_ptr];
 			}
 			(*unk_kw)[key] = value;
 		}
diff --git a/test/issue-311/CMakeLists.txt b/test/issue-311/CMakeLists.txt
new file mode 100644
index 0000000..19b5b8c
--- /dev/null
+++ b/test/issue-311/CMakeLists.txt
@@ -0,0 +1,3 @@
+add_test_simple_schema(Issue::311
+                       ${CMAKE_CURRENT_SOURCE_DIR}/schema.json
+                       ${CMAKE_CURRENT_SOURCE_DIR}/instance.json)
diff --git a/test/issue-311/instance.json b/test/issue-311/instance.json
new file mode 100644
index 0000000..e571d98
--- /dev/null
+++ b/test/issue-311/instance.json
@@ -0,0 +1,3 @@
+{
+  "element": [1]
+}
diff --git a/test/issue-311/schema.json b/test/issue-311/schema.json
new file mode 100644
index 0000000..3be1b40
--- /dev/null
+++ b/test/issue-311/schema.json
@@ -0,0 +1,19 @@
+{
+  "type": "object",
+  "properties": {
+    "element": {
+      "$ref": "#/$defs/element"
+    }
+  },
+  "$defs": {
+    "element": {
+      "type": "array",
+      "items": [
+        {
+          "$comment": "the comment should not lead to fail of loading schema",
+          "type": "number"
+        }
+      ]
+    }
+  }
+}