diff --git a/index.js b/index.js
index d1a082e..ea0b3a5 100644
--- a/index.js
+++ b/index.js
@@ -98,7 +98,9 @@ class RefResolver {
 
       const targetSchema = this.getDerefSchema(refSchemaId, refJsonPointer)
       if (targetSchema === null) {
-        throw new Error(`Cannot resolve ref "${ref.ref}".`)
+        throw new Error(
+          `Cannot resolve ref "${ref.ref}". Ref ${refJsonPointer} is not found in schema "${refSchemaId}".`
+        )
       }
 
       ref.targetSchema = targetSchema
diff --git a/test/deref-schema.test.js b/test/deref-schema.test.js
index d0b196b..8d35d7b 100644
--- a/test/deref-schema.test.js
+++ b/test/deref-schema.test.js
@@ -228,6 +228,9 @@ test('should throw if target ref schema is not found', () => {
   try {
     refResolver.derefSchema('relativeAddress')
   } catch (error) {
-    assert.strictEqual(error.message, 'Cannot resolve ref "#foo".')
+    assert.strictEqual(
+      error.message,
+      'Cannot resolve ref "#foo". Ref #foo is not found in schema "relativeAddress".'
+    )
   }
 })