diff --git a/src/QueryComplexity.ts b/src/QueryComplexity.ts
index 091f45c..41dee1e 100644
--- a/src/QueryComplexity.ts
+++ b/src/QueryComplexity.ts
@@ -174,12 +174,18 @@ export default class QueryComplexity {
 
     // Get variable values from variables that are passed from options, merged
     // with default values defined in the operation
-    this.variableValues = getVariableValues(
+    const { coerced, errors } = getVariableValues(
       this.context.getSchema(),
       // We have to create a new array here because input argument is not readonly in graphql ~14.6.0
       operation.variableDefinitions ? [...operation.variableDefinitions] : [],
       this.options.variables ?? {}
-    ).coerced;
+    );
+    if (errors && errors.length) {
+      // We have input validation errors, report errors and abort
+      errors.forEach((error) => this.context.reportError(error));
+      return;
+    }
+    this.variableValues = coerced;
 
     switch (operation.operation) {
       case 'query':
diff --git a/src/__tests__/QueryComplexity-test.ts b/src/__tests__/QueryComplexity-test.ts
index 6c22ae3..92269dd 100644
--- a/src/__tests__/QueryComplexity-test.ts
+++ b/src/__tests__/QueryComplexity-test.ts
@@ -254,21 +254,28 @@ describe('QueryComplexity analysis', () => {
     expect(visitor.complexity).to.equal(0);
   });
 
-  it('should ignore unused variables', () => {
+  it('should report errors for unused variables', () => {
     const ast = parse(`
       query ($unusedVar: ID!) {
         variableScalar(count: 100)
       }
     `);
 
-    const context = new CompatibleValidationContext(schema, ast, typeInfo);
-    const visitor = new ComplexityVisitor(context, {
-      maximumComplexity: 100,
-      estimators: [simpleEstimator({ defaultComplexity: 10 })],
-    });
-
-    visit(ast, visitWithTypeInfo(typeInfo, visitor));
-    expect(visitor.complexity).to.equal(10);
+    const errors = validate(schema, ast, [
+      createComplexityRule({
+        maximumComplexity: 1000,
+        estimators: [
+          simpleEstimator({
+            defaultComplexity: 1,
+          }),
+        ],
+        variables: {
+          unusedVar: 'someID',
+        },
+      }),
+    ]);
+    expect(errors).to.have.length(1);
+    expect(errors[0].message).to.contain('$unusedVar');
   });
 
   it('should ignore unknown field', () => {
@@ -860,4 +867,28 @@ describe('QueryComplexity analysis', () => {
     // query.scalar(5) + query.requiredArgs(5) * requiredArgs.scalar(5)
     expect(complexity).to.equal(30);
   });
+
+  it('reports variable coercion errors', () => {
+    const ast = parse(`
+      query ($input: RGB!){
+        enumInputArg(enum: $input)
+      }
+    `);
+
+    const errors = validate(schema, ast, [
+      createComplexityRule({
+        maximumComplexity: 1000,
+        estimators: [
+          simpleEstimator({
+            defaultComplexity: 1,
+          }),
+        ],
+        variables: {
+          input: 'INVALIDVALUE',
+        },
+      }),
+    ]);
+    expect(errors).to.have.length(1);
+    expect(errors[0].message).to.contain('INVALIDVALUE');
+  });
 });
diff --git a/src/__tests__/fixtures/schema.ts b/src/__tests__/fixtures/schema.ts
index 5a2d30b..415994a 100644
--- a/src/__tests__/fixtures/schema.ts
+++ b/src/__tests__/fixtures/schema.ts
@@ -164,6 +164,14 @@ const Query = new GraphQLObjectType({
         },
       },
     },
+    enumInputArg: {
+      type: GraphQLString,
+      args: {
+        enum: {
+          type: EnumType,
+        },
+      },
+    },
     _service: { type: SDLInterface },
   }),
   interfaces: () => [NameInterface, UnionInterface],