diff --git a/packager/media/formats/webvtt/webvtt_to_mp4_handler_unittest.cc b/packager/media/formats/webvtt/webvtt_to_mp4_handler_unittest.cc
index 28c23b5de8..ab6c291950 100644
--- a/packager/media/formats/webvtt/webvtt_to_mp4_handler_unittest.cc
+++ b/packager/media/formats/webvtt/webvtt_to_mp4_handler_unittest.cc
@@ -17,6 +17,10 @@ namespace {
 const size_t kStreamIndex = 0;
 const bool kSubSegment = true;
 const bool kEncrypted = true;
+
+const char* kId1 = "sample-id-1";
+const char* kId2 = "sample-id-2";
+const char* kId3 = "sample-id-3";
 }  // namespace
 
 class WebVttToMp4HandlerTest : public MediaHandlerTestBase {
@@ -45,11 +49,12 @@ class WebVttToMp4HandlerTest : public MediaHandlerTestBase {
         StreamData::FromStreamInfo(kStreamIndex, std::move(info)));
   }
 
-  Status DispatchText(int64_t start_time, int64_t end_time) {
-    const std::string kId = "id";
+  Status DispatchText(const std::string& id,
+                      int64_t start_time,
+                      int64_t end_time) {
     const std::string kPayload = "payload";
 
-    auto sample = GetTextSample(kId, start_time, end_time, kPayload);
+    auto sample = GetTextSample(id, start_time, end_time, kPayload);
     return In()->Dispatch(
         StreamData::FromTextSample(kStreamIndex, std::move(sample)));
   }
@@ -110,7 +115,7 @@ TEST_F(WebVttToMp4HandlerTest, NonZeroStartTime) {
   }
 
   ASSERT_OK(DispatchStream());
-  ASSERT_OK(DispatchText(kSampleStart, kSampleEnd));
+  ASSERT_OK(DispatchText(kId1, kSampleStart, kSampleEnd));
   ASSERT_OK(DispatchSegment(kSegmentStart, kSegmentEnd));
   ASSERT_OK(Flush());
 }
@@ -166,8 +171,8 @@ TEST_F(WebVttToMp4HandlerTest, NoOverlap) {
   }
 
   ASSERT_OK(DispatchStream());
-  ASSERT_OK(DispatchText(kSample1Start, kSample1End));
-  ASSERT_OK(DispatchText(kSample2Start, kSample2End));
+  ASSERT_OK(DispatchText(kId1, kSample1Start, kSample1End));
+  ASSERT_OK(DispatchText(kId2, kSample2Start, kSample2End));
   ASSERT_OK(DispatchSegment(kSegmentStart, kSegmentEnd));
   ASSERT_OK(Flush());
 }
@@ -230,8 +235,8 @@ TEST_F(WebVttToMp4HandlerTest, Overlap) {
   }
 
   ASSERT_OK(DispatchStream());
-  ASSERT_OK(DispatchText(kSample1Start, kSample1End));
-  ASSERT_OK(DispatchText(kSample2Start, kSample2End));
+  ASSERT_OK(DispatchText(kId1, kSample1Start, kSample1End));
+  ASSERT_OK(DispatchText(kId2, kSample2Start, kSample2End));
   ASSERT_OK(DispatchSegment(kSegmentStart, kSegmentEnd));
   ASSERT_OK(Flush());
 }
@@ -296,8 +301,8 @@ TEST_F(WebVttToMp4HandlerTest, Contains) {
   }
 
   ASSERT_OK(DispatchStream());
-  ASSERT_OK(DispatchText(kSample1Start, kSample1End));
-  ASSERT_OK(DispatchText(kSample2Start, kSample2End));
+  ASSERT_OK(DispatchText(kId1, kSample1Start, kSample1End));
+  ASSERT_OK(DispatchText(kId2, kSample2Start, kSample2End));
   ASSERT_OK(DispatchSegment(kSegmentStart, kSegmentEnd));
   ASSERT_OK(Flush());
 }
@@ -337,8 +342,8 @@ TEST_F(WebVttToMp4HandlerTest, ExactOverlap) {
   }
 
   ASSERT_OK(DispatchStream());
-  ASSERT_OK(DispatchText(kSampleStart, kSampleEnd));
-  ASSERT_OK(DispatchText(kSampleStart, kSampleEnd));
+  ASSERT_OK(DispatchText(kId1, kSampleStart, kSampleEnd));
+  ASSERT_OK(DispatchText(kId2, kSampleStart, kSampleEnd));
   ASSERT_OK(DispatchSegment(kSegmentStart, kSegmentEnd));
   ASSERT_OK(Flush());
 }
@@ -404,9 +409,9 @@ TEST_F(WebVttToMp4HandlerTest, OverlapStartWithStaggerEnd) {
   }
 
   ASSERT_OK(DispatchStream());
-  ASSERT_OK(DispatchText(kSample1Start, kSample1End));
-  ASSERT_OK(DispatchText(kSample2Start, kSample2End));
-  ASSERT_OK(DispatchText(kSample3Start, kSample3End));
+  ASSERT_OK(DispatchText(kId1, kSample1Start, kSample1End));
+  ASSERT_OK(DispatchText(kId2, kSample2Start, kSample2End));
+  ASSERT_OK(DispatchText(kId3, kSample3Start, kSample3End));
   ASSERT_OK(DispatchSegment(kSegmentStart, kSegmentEnd));
   ASSERT_OK(Flush());
 }
@@ -472,9 +477,9 @@ TEST_F(WebVttToMp4HandlerTest, StaggerStartWithOverlapEnd) {
   }
 
   ASSERT_OK(DispatchStream());
-  ASSERT_OK(DispatchText(kSample1Start, kSample1End));
-  ASSERT_OK(DispatchText(kSample2Start, kSample2End));
-  ASSERT_OK(DispatchText(kSample3Start, kSample3End));
+  ASSERT_OK(DispatchText(kId1, kSample1Start, kSample1End));
+  ASSERT_OK(DispatchText(kId2, kSample2Start, kSample2End));
+  ASSERT_OK(DispatchText(kId3, kSample3Start, kSample3End));
   ASSERT_OK(DispatchSegment(kSegmentStart, kSegmentEnd));
   ASSERT_OK(Flush());
 }
@@ -539,9 +544,9 @@ TEST_F(WebVttToMp4HandlerTest, CrossSegmentSamples) {
   }
 
   ASSERT_OK(DispatchStream());
-  ASSERT_OK(DispatchText(kSampleStart, kSampleEnd));
+  ASSERT_OK(DispatchText(kId1, kSampleStart, kSampleEnd));
   ASSERT_OK(DispatchSegment(kSegment1Start, kSegment1End));
-  ASSERT_OK(DispatchText(kSampleStart, kSampleEnd));
+  ASSERT_OK(DispatchText(kId1, kSampleStart, kSampleEnd));
   ASSERT_OK(DispatchSegment(kSegment2Start, kSegment2End));
   ASSERT_OK(Flush());
 }