diff --git a/common/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java b/common/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java
index f8289c1fdcda..41c511a11048 100644
--- a/common/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java
+++ b/common/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java
@@ -993,7 +993,7 @@ public static UTF8String concatWs(UTF8String separator, UTF8String... inputs) {
       return null;
     }
 
-    int numInputBytes = 0;  // total number of bytes from the inputs
+    long numInputBytes = 0L;  // total number of bytes from the inputs
     int numInputs = 0;      // number of non-null inputs
     for (int i = 0; i < inputs.length; i++) {
       if (inputs[i] != null) {
@@ -1009,7 +1009,8 @@ public static UTF8String concatWs(UTF8String separator, UTF8String... inputs) {
 
     // Allocate a new byte array, and copy the inputs one by one into it.
     // The size of the new array is the size of all inputs, plus the separators.
-    final byte[] result = new byte[numInputBytes + (numInputs - 1) * separator.numBytes];
+    int resultSize = Math.toIntExact(numInputBytes + (numInputs - 1) * (long)separator.numBytes);
+    final byte[] result = new byte[resultSize];
     int offset = 0;
 
     for (int i = 0, j = 0; i < inputs.length; i++) {