diff --git a/CHANGELOG.md b/CHANGELOG.md
index 40b59d2336..1d7493899a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,7 @@ For experimental package changes, see the [experimental CHANGELOG](experimental/
 
 * fix(sdk-node): avoid spurious diag errors for unknown OTEL_NODE_RESOURCE_DETECTORS values [#4879](https://github.com/open-telemetry/opentelemetry-js/pull/4879) @trentm
 * deps(opentelemetry-instrumentation): Bump `shimmer` types to 1.2.0 [#4865](https://github.com/open-telemetry/opentelemetry-js/pull/4865) @lforst
+* fix(instrumentation): Fix optional property types [#4833](https://github.com/open-telemetry/opentelemetry-js/pull/4833) @alecmev
 
 ### :books: (Refine Doc)
 
diff --git a/experimental/packages/opentelemetry-instrumentation/src/types.ts b/experimental/packages/opentelemetry-instrumentation/src/types.ts
index 2fa567ff01..b58054ac0d 100644
--- a/experimental/packages/opentelemetry-instrumentation/src/types.ts
+++ b/experimental/packages/opentelemetry-instrumentation/src/types.ts
@@ -136,11 +136,15 @@ export interface InstrumentationModuleDefinition {
 
   /** Method to patch the instrumentation  */
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  patch?: (moduleExports: any, moduleVersion?: string) => any;
+  patch?:
+    | ((moduleExports: any, moduleVersion?: string | undefined) => any)
+    | undefined;
 
   /** Method to unpatch the instrumentation  */
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  unpatch?: (moduleExports: any, moduleVersion?: string) => void;
+  unpatch?:
+    | ((moduleExports: any, moduleVersion?: string | undefined) => void)
+    | undefined;
 }
 
 /**