diff --git a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/creator/name/InputFileSegmentNameGenerator.java b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/creator/name/InputFileSegmentNameGenerator.java
index 1d703832373e..3f7e2c387d24 100644
--- a/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/creator/name/InputFileSegmentNameGenerator.java
+++ b/pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/creator/name/InputFileSegmentNameGenerator.java
@@ -86,7 +86,11 @@ private String makeSegmentName() {
     } else {
       segmentName = _segmentNameTemplate;
       for (int i = 1; i <= m.groupCount(); i++) {
-        segmentName = segmentName.replace(String.format(PARAMETER_TEMPLATE, i), m.group(i));
+        String value = m.group(i);
+        if (value == null) {
+          value = "";
+        }
+        segmentName = segmentName.replace(String.format(PARAMETER_TEMPLATE, i), value);
       }
     }
     return _appendUUIDToSegmentName ? JOINER.join(segmentName, UUID.randomUUID()) : segmentName;
diff --git a/pinot-segment-spi/src/test/java/org/apache/pinot/segment/spi/creator/name/InputFileSegmentNameGeneratorTest.java b/pinot-segment-spi/src/test/java/org/apache/pinot/segment/spi/creator/name/InputFileSegmentNameGeneratorTest.java
index 7ce23d83f0d0..11836de846dc 100644
--- a/pinot-segment-spi/src/test/java/org/apache/pinot/segment/spi/creator/name/InputFileSegmentNameGeneratorTest.java
+++ b/pinot-segment-spi/src/test/java/org/apache/pinot/segment/spi/creator/name/InputFileSegmentNameGeneratorTest.java
@@ -29,25 +29,37 @@ public class InputFileSegmentNameGeneratorTest {
 
   @Test
   public void testWithInvalidPath() {
-    validateName("/my/path/to/segmentname.tsv", "my_path_to_segmentname_tsv");
-    validateName("hdfs:///my/path/to/segmentname.tsv", "my_path_to_segmentname_tsv");
+    validateCSVFileName("/my/path/to/segmentname.tsv", "my_path_to_segmentname_tsv");
+    validateCSVFileName("hdfs:///my/path/to/segmentname.tsv", "my_path_to_segmentname_tsv");
   }
 
   @Test
   public void testWithHDFSPath() {
-    validateName("hdfs:///my/path/to/segmentname.csv", "segmentname");
-    validateName("hdfs:/server:9000//my/path/to/segmentname.csv", "segmentname");
+    validateCSVFileName("hdfs:///my/path/to/segmentname.csv", "segmentname");
+    validateCSVFileName("hdfs:/server:9000//my/path/to/segmentname.csv", "segmentname");
   }
 
   @Test
   public void testWithFilePath() {
-    validateName("file:///my/path/to/segmentname.csv", "segmentname");
+    validateCSVFileName("file:///my/path/to/segmentname.csv", "segmentname");
   }
 
-  private void validateName(String inputFileUriAsStr, String segmentName) {
+  @Test
+  public void testWithOptionalPattern() {
+    String pattern = ".+/(\\w+)(\\.csv)?";
+    String template = "${filePathPattern:\\1}";
+    validateName("file:///my/path/to/segmentname.csv", "segmentname", pattern, template);
+    validateName("file:///my/path/to/segmentname", "segmentname", pattern, template);
+  }
+
+  private void validateCSVFileName(String inputFileUriAsStr, String segmentName) {
+    String pattern = ".+/(.+)\\.csv";
+    String template = "${filePathPattern:\\1}";
+    validateName(inputFileUriAsStr, segmentName, pattern, template);
+  }
+
+  private void validateName(String inputFileUriAsStr, String segmentName, String pattern, String template) {
     try {
-      String pattern = ".+/(.+)\\.csv";
-      String template = "${filePathPattern:\\1}";
       SegmentNameGenerator segmentNameGenerator =
           new InputFileSegmentNameGenerator(pattern, template, inputFileUriAsStr);
       assertEquals(segmentNameGenerator.generateSegmentName(INVALID_SEQUENCE_ID, null, null), segmentName);