diff --git a/packages/jsii/lib/validator.ts b/packages/jsii/lib/validator.ts
index 6f5aebcc1a..aedaa7d771 100644
--- a/packages/jsii/lib/validator.ts
+++ b/packages/jsii/lib/validator.ts
@@ -392,6 +392,14 @@ function _defaultValidations(): ValidationFunction[] {
       label: string,
       action: string,
     ) {
+      if (!!expected.protected !== !!actual.protected) {
+        const expVisibility = expected.protected ? 'protected' : 'public';
+        const actVisibility = actual.protected ? 'protected' : 'public';
+        diagnostic(
+          ts.DiagnosticCategory.Error,
+          `${label} changes visibility when ${action} (expected ${expVisibility}, found ${actVisibility})`,
+        );
+      }
       if (!deepEqual(actual.returns, expected.returns)) {
         const expType = spec.describeTypeReference(expected.returns?.type);
         const actType = spec.describeTypeReference(actual.returns?.type);
@@ -446,6 +454,14 @@ function _defaultValidations(): ValidationFunction[] {
       label: string,
       action: string,
     ) {
+      if (!!expected.protected !== !!actual.protected) {
+        const expVisibility = expected.protected ? 'protected' : 'public';
+        const actVisibility = actual.protected ? 'protected' : 'public';
+        diagnostic(
+          ts.DiagnosticCategory.Error,
+          `${label} changes visibility when ${action} (expected ${expVisibility}, found ${actVisibility})`,
+        );
+      }
       if (!deepEqual(expected.type, actual.type)) {
         const expType = spec.describeTypeReference(expected.type);
         const actType = spec.describeTypeReference(actual.type);
diff --git a/packages/jsii/test/__snapshots__/negatives.test.js.snap b/packages/jsii/test/__snapshots__/negatives.test.js.snap
index d42c6919fc..d9b1f709a2 100644
--- a/packages/jsii/test/__snapshots__/negatives.test.js.snap
+++ b/packages/jsii/test/__snapshots__/negatives.test.js.snap
@@ -436,6 +436,12 @@ exports[`omit.4 1`] = `
 "
 `;
 
+exports[`override-changes-visibility 1`] = `
+"error TS0: jsii.ChildClass#method changes visibility when overriding jsii.BaseClass (expected protected, found public)
+error TS0: jsii.ChildClass#property changes visibility when overriding jsii.BaseClass (expected protected, found public)
+"
+`;
+
 exports[`prohibited-member-name 1`] = `
 "neg.prohibited-member-name.ts:4:3 - error TS9999: JSII: Prohibited member name: equals
 
diff --git a/packages/jsii/test/negatives/neg.override-changes-visibility.ts b/packages/jsii/test/negatives/neg.override-changes-visibility.ts
new file mode 100644
index 0000000000..92f096defd
--- /dev/null
+++ b/packages/jsii/test/negatives/neg.override-changes-visibility.ts
@@ -0,0 +1,20 @@
+// Note: not testing "public -> protected" because this is invalid TypeScript,
+//       so the type checker will already have caught it for us.
+
+export class BaseClass {
+  protected readonly property?: string;
+
+  protected method() {
+    return;
+  }
+}
+
+export class ChildClass extends BaseClass {
+  // This property cannot be public as it overrides the one on BaseClass which is protected
+  public readonly property?: string;
+
+  // This method cannot be public as it overrides the one on BaseClass which is protected
+  public method() {
+    throw new Error('Not Implemented');
+  }
+}