diff --git a/plugins/node/opentelemetry-instrumentation-fastify/src/instrumentation.ts b/plugins/node/opentelemetry-instrumentation-fastify/src/instrumentation.ts
index f2f51e6885..4ef2e9b87a 100644
--- a/plugins/node/opentelemetry-instrumentation-fastify/src/instrumentation.ts
+++ b/plugins/node/opentelemetry-instrumentation-fastify/src/instrumentation.ts
@@ -75,7 +75,12 @@ export class FastifyInstrumentation extends InstrumentationBase {
         ['^3.0.0', '^4.0.0'],
         (moduleExports, moduleVersion) => {
           this._diag.debug(`Applying patch for fastify@${moduleVersion}`);
-          return this._patchConstructor(moduleExports);
+          const wrappedFastify = this._wrapFastify();
+
+          this._wrap(moduleExports, 'fastify', wrappedFastify);
+          this._wrap(moduleExports, 'default', wrappedFastify);
+
+          return moduleExports;
         }
       ),
     ];
@@ -197,25 +202,22 @@ export class FastifyInstrumentation extends InstrumentationBase {
     };
   }
 
-  private _patchConstructor(
-    moduleExports: { fastify: () => FastifyInstance },
-    ): () => FastifyInstance {
+  private _wrapFastify(): (
+    original: () => FastifyInstance
+  ) => () => FastifyInstance {
     const instrumentation = this;
-    this._diag.debug('Patching fastify constructor function');
 
-    function fastify(this: FastifyInstance, ...args: any) {
-      const app: FastifyInstance = moduleExports.fastify.apply(this, args);
-      app.addHook('onRequest', instrumentation._hookOnRequest());
-      app.addHook('preHandler', instrumentation._hookPreHandler());
+    return function (original): () => FastifyInstance {
+      return function wrappedFastify(this: FastifyInstance, ...args: any) {
+        const app: FastifyInstance = original.apply(this, args);
+        app.addHook('onRequest', instrumentation._hookOnRequest());
+        app.addHook('preHandler', instrumentation._hookPreHandler());
 
-      instrumentation._wrap(app, 'addHook', instrumentation._wrapAddHook());
+        instrumentation._wrap(app, 'addHook', instrumentation._wrapAddHook());
 
-      return app;
-    }
-
-    fastify.fastify = fastify;
-    fastify.default = fastify;
-    return fastify;
+        return app;
+      };
+    };
   }
 
   private _patchSend() {