diff --git a/src/index.ts b/src/index.ts
index fd450047..438f6d36 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -358,15 +358,17 @@ class EsbuildServerlessPlugin implements ServerlessPlugin {
     };
 
     for (const fn of Object.values(this.functions)) {
+      const patterns = [
+        ...new Set([
+          ...(fn.package?.include || []),
+          ...(fn.package?.exclude || []).map(concat('!')),
+          ...(fn.package?.patterns || []),
+        ]),
+      ];
+
       fn.package = {
         ...(fn.package || {}),
-        patterns: [
-          ...new Set([
-            ...(fn.package?.include || []),
-            ...(fn.package?.exclude || []).map(concat('!')),
-            ...(fn.package?.patterns || []),
-          ]),
-        ],
+        ...(patterns.length && { patterns }),
       };
     }
   }
diff --git a/src/pack.ts b/src/pack.ts
index 01ff27dc..6d9af2c1 100644
--- a/src/pack.ts
+++ b/src/pack.ts
@@ -179,13 +179,13 @@ export async function pack(this: EsbuildServerlessPlugin) {
 
     const bundleExcludedFiles = bundlePathList.filter((item) => !bundlePath.startsWith(item)).map(trimExtension);
 
-    assert(func.package?.patterns);
+    const functionPackagePatterns = func.package?.patterns || [];
 
-    const functionExclusionPatterns = func.package.patterns
+    const functionExclusionPatterns = functionPackagePatterns
       .filter((pattern) => pattern.charAt(0) === '!')
       .map((pattern) => pattern.slice(1));
 
-    const functionFiles = await globby(func.package.patterns, { cwd: buildDirPath });
+    const functionFiles = await globby(functionPackagePatterns, { cwd: buildDirPath });
     const functionExcludedFiles = (await globby(functionExclusionPatterns, { cwd: buildDirPath })).map(trimExtension);
 
     const includedFiles = [...packageFiles, ...functionFiles];
diff --git a/src/tests/index.test.ts b/src/tests/index.test.ts
index d9fbbc65..7a15ce8d 100644
--- a/src/tests/index.test.ts
+++ b/src/tests/index.test.ts
@@ -39,6 +39,17 @@ const packageService: Partial<Service> = {
   getFunction: mockGetFunction,
 };
 
+const patternsService: Partial<Service> = {
+  functions: {
+    hello1: { handler: 'hello1.handler', events: [] },
+    hello2: { handler: 'hello2.handler', events: [], package: {} },
+    hello3: { handler: 'hello3.handler', events: [], package: { patterns: ['excluded-by-default.json'] } },
+  },
+  package: { patterns: ['!excluded-by-default.json'] },
+  provider: mockProvider,
+  getFunction: mockGetFunction,
+};
+
 const mockServerlessConfig = (serviceOverride?: Partial<Service>): Serverless => {
   const service = {
     ...packageIndividuallyService,
@@ -223,3 +234,39 @@ describe('Move Artifacts', () => {
     });
   });
 });
+
+describe('Prepare', () => {
+  describe('function package', () => {
+    it('should set package patterns on functions only if supplied', () => {
+      const plugin = new EsbuildServerlessPlugin(mockServerlessConfig(patternsService), mockOptions);
+
+      plugin.hooks.initialize?.();
+
+      plugin.prepare();
+
+      expect(plugin.functions).toMatchInlineSnapshot(`
+        {
+          "hello1": {
+            "events": [],
+            "handler": "hello1.handler",
+            "package": {},
+          },
+          "hello2": {
+            "events": [],
+            "handler": "hello2.handler",
+            "package": {},
+          },
+          "hello3": {
+            "events": [],
+            "handler": "hello3.handler",
+            "package": {
+              "patterns": [
+                "excluded-by-default.json",
+              ],
+            },
+          },
+        }
+      `);
+    });
+  });
+});
diff --git a/src/tests/pack.test.ts b/src/tests/pack.test.ts
index 1c121804..f03c6f4a 100644
--- a/src/tests/pack.test.ts
+++ b/src/tests/pack.test.ts
@@ -75,7 +75,7 @@ describe('pack', () => {
             handler: 'hello1.handler',
             events: [{ http: { path: 'hello', method: 'get' } }],
             name: 'serverless-example-dev-hello1',
-            package: { patterns: [] },
+            package: {},
           },
           functionAlias: 'hello1',
         },
@@ -85,7 +85,7 @@ describe('pack', () => {
             handler: 'hello2.handler',
             events: [{ http: { path: 'hello', method: 'get' } }],
             name: 'serverless-example-dev-hello2',
-            package: { patterns: [] },
+            package: {},
           },
           functionAlias: 'hello2',
         },
@@ -147,7 +147,7 @@ describe('pack', () => {
             handler: 'hello1.handler',
             events: [{ http: { path: 'hello', method: 'get' } }],
             name: 'serverless-example-dev-hello1',
-            package: { patterns: [] },
+            package: {},
           },
           functionAlias: 'hello1',
         },
@@ -157,7 +157,7 @@ describe('pack', () => {
             handler: 'hello2.handler',
             events: [{ http: { path: 'hello', method: 'get' } }],
             name: 'serverless-example-dev-hello2',
-            package: { patterns: [] },
+            package: {},
           },
           functionAlias: 'hello2',
         },