diff --git a/src/validation/rules/default_values_of_correct_type.rs b/src/validation/rules/default_values_of_correct_type.rs
index 1b14181e..0ae56a99 100644
--- a/src/validation/rules/default_values_of_correct_type.rs
+++ b/src/validation/rules/default_values_of_correct_type.rs
@@ -1,3 +1,5 @@
+use async_graphql_parser::types::BaseType;
+
 use crate::context::QueryPathNode;
 use crate::parser::types::VariableDefinition;
 use crate::validation::utils::is_valid_input_value;
@@ -12,6 +14,13 @@ impl<'a> Visitor<'a> for DefaultValuesOfCorrectType {
         ctx: &mut VisitorContext<'a>,
         variable_definition: &'a Positioned<VariableDefinition>,
     ) {
+        if let BaseType::Named(vtype_name) = &variable_definition.node.var_type.node.base {
+          if !ctx.registry.types.contains_key(vtype_name.as_str()) {
+              ctx.report_error(vec![variable_definition.pos], format!(r#"Unknown type "{}""#, vtype_name));
+              return;
+          }
+        }
+
         if let Some(value) = &variable_definition.node.default_value {
             if !variable_definition.node.var_type.node.nullable {
                 ctx.report_error(vec![variable_definition.pos],format!(
diff --git a/tests/variables.rs b/tests/variables.rs
index 8cd8c376..70b0f8bb 100644
--- a/tests/variables.rs
+++ b/tests/variables.rs
@@ -297,3 +297,61 @@ pub async fn test_variables_json() {
         })
     );
 }
+
+#[tokio::test]
+pub async fn test_variables_invalid_type() {
+    struct Query;
+
+    #[Object]
+    impl Query {
+        pub async fn int_val(&self, value: Option<i32>) -> i32 {
+            value.unwrap_or(10)
+        }
+    }
+
+    let schema = Schema::new(Query, EmptyMutation, EmptySubscription);
+    let query = Request::new(
+        r#"
+            query QueryWithVariables($intVal: invalid) {
+                intVal(value: $intVal)
+            }
+        "#,
+    )
+    .variables(Variables::from_value(value!({
+        "intVal": null,
+    })));
+    let resp = schema.execute(query).await;
+    assert_eq!(
+        resp.errors.first().map(|v| v.message.as_str()),
+        Some("Unknown type \"invalid\"")
+    );
+}
+
+#[tokio::test]
+pub async fn test_variables_invalid_type_with_value() {
+    struct Query;
+
+    #[Object]
+    impl Query {
+        pub async fn int_val(&self, value: Option<i32>) -> i32 {
+            value.unwrap_or(10)
+        }
+    }
+
+    let schema = Schema::new(Query, EmptyMutation, EmptySubscription);
+    let query = Request::new(
+        r#"
+            query QueryWithVariables($intVal: invalid = 2) {
+                intVal(value: $intVal)
+            }
+        "#,
+    )
+    .variables(Variables::from_value(value!({
+        "intVal": null,
+    })));
+    let resp = schema.execute(query).await;
+    assert_eq!(
+        resp.errors.first().map(|v| v.message.as_str()),
+        Some("Unknown type \"invalid\"")
+    );
+}