diff --git a/package-lock.json b/package-lock.json
index 13c46ad..ff56c99 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,11 +1,11 @@
 {
   "name": "xlstream",
-  "version": "2.5.0",
+  "version": "2.5.1",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
-      "version": "2.5.0",
+      "version": "2.5.1",
       "license": "MIT",
       "dependencies": {
         "deep-rename-keys": "^0.2.1",
diff --git a/src/index.ts b/src/index.ts
index 9d4d31f..ad16619 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -48,7 +48,7 @@ function getFilledHeader(arr: any[], header: any[]) {
         return header;
     }
     const filledHeader = [];
-    for (let i = 0; i < arr.length; i++) {
+    for (let i = 0; i < Math.max(arr.length, header.length); i++) {
         filledHeader.push(
             header[i] ? header[i] : `[${numbersToLetter(i + 1)}]`
         );
diff --git a/tests/__snapshots__/xlsx-stream.spec.ts.snap b/tests/__snapshots__/xlsx-stream.spec.ts.snap
index a0c0ef5..0767f03 100644
--- a/tests/__snapshots__/xlsx-stream.spec.ts.snap
+++ b/tests/__snapshots__/xlsx-stream.spec.ts.snap
@@ -1345,8 +1345,9 @@ Array [
       "column1",
       "column2",
       "column3",
+      "column4",
     ],
-    "processedSheetSize": 1246,
+    "processedSheetSize": 2343,
     "raw": Object {
       "arr": Array [
         "hello",
@@ -1358,7 +1359,41 @@ Array [
         "column3": 123.123,
       },
     },
-    "totalSheetSize": 1246,
+    "totalSheetSize": 2343,
+  },
+  Object {
+    "formatted": Object {
+      "arr": Array [
+        undefined,
+        "world",
+        undefined,
+        456,
+      ],
+      "obj": Object {
+        "column2": "world",
+        "column4": 456,
+      },
+    },
+    "header": Array [
+      "column1",
+      "column2",
+      "column3",
+      "column4",
+    ],
+    "processedSheetSize": 2343,
+    "raw": Object {
+      "arr": Array [
+        undefined,
+        "world",
+        undefined,
+        456,
+      ],
+      "obj": Object {
+        "column2": "world",
+        "column4": 456,
+      },
+    },
+    "totalSheetSize": 2343,
   },
 ]
 `;
diff --git a/tests/assets/with-header.xlsx b/tests/assets/with-header.xlsx
index b509c27..19f1bb8 100644
Binary files a/tests/assets/with-header.xlsx and b/tests/assets/with-header.xlsx differ