diff --git a/src/Utils/removeUnreachable.ts b/src/Utils/removeUnreachable.ts
index 430ccb1ed..479c99d89 100644
--- a/src/Utils/removeUnreachable.ts
+++ b/src/Utils/removeUnreachable.ts
@@ -39,7 +39,7 @@ function addReachable(
         }
     } else if (definition.not) {
         addReachable(definition.not, definitions, reachable);
-    } else if (definition.type === "object") {
+    } else if (definition.type?.includes("object")) {
         for (const prop in definition.properties || {}) {
             const propDefinition = definition.properties![prop];
             addReachable(propDefinition, definitions, reachable);
@@ -49,7 +49,7 @@ function addReachable(
         if (additionalProperties) {
             addReachable(additionalProperties, definitions, reachable);
         }
-    } else if (definition.type === "array") {
+    } else if (definition.type?.includes("array")) {
         const items = definition.items;
         if (Array.isArray(items)) {
             for (const item of items) {
diff --git a/test/valid-data-annotations.test.ts b/test/valid-data-annotations.test.ts
index 4cead7918..ffa9e1ba1 100644
--- a/test/valid-data-annotations.test.ts
+++ b/test/valid-data-annotations.test.ts
@@ -73,4 +73,6 @@ describe("valid-data-annotations", () => {
     it("annotation-writeOnly", assertValidSchema("annotation-writeOnly", "MyObject", "basic"));
 
     it("annotation-union-if-then", assertValidSchema("annotation-union-if-then", "Animal", "basic"));
+
+    it("annotation-nullable-definition", assertValidSchema("annotation-nullable-definition", "MyObject", "extended"));
 });
diff --git a/test/valid-data/annotation-nullable-definition/main.ts b/test/valid-data/annotation-nullable-definition/main.ts
new file mode 100644
index 000000000..b78627f98
--- /dev/null
+++ b/test/valid-data/annotation-nullable-definition/main.ts
@@ -0,0 +1,10 @@
+export class Definition {
+     name: string
+}
+
+export class MyObject  {
+    /**
+     * @nullable
+     */
+    optional?: Definition[]
+}
diff --git a/test/valid-data/annotation-nullable-definition/schema.json b/test/valid-data/annotation-nullable-definition/schema.json
new file mode 100644
index 000000000..217292f05
--- /dev/null
+++ b/test/valid-data/annotation-nullable-definition/schema.json
@@ -0,0 +1,33 @@
+{
+  "$schema":"http://json-schema.org/draft-07/schema#",
+  "$ref":"#/definitions/MyObject",
+  "definitions":{
+     "MyObject":{
+        "type":"object",
+        "properties":{
+           "optional":{
+              "type":[
+                 "array",
+                 "null"
+              ],
+              "items":{
+                 "$ref":"#/definitions/Definition"
+              }
+           }
+        },
+        "additionalProperties":false
+     },
+     "Definition":{
+        "type":"object",
+        "properties":{
+           "name":{
+              "type":"string"
+           }
+        },
+        "required":[
+           "name"
+        ],
+        "additionalProperties":false
+     }
+  }
+}