diff --git a/dom/media/wave/WaveDemuxer.cpp b/dom/media/wave/WaveDemuxer.cpp
index 64d1eec6ba6c..18a2376aeed0 100644
--- a/dom/media/wave/WaveDemuxer.cpp
+++ b/dom/media/wave/WaveDemuxer.cpp
@@ -113,8 +113,6 @@ WAVTrackDemuxer::Init()
     uint32_t aChunkName = mHeaderParser.GiveHeader().ChunkName();
     uint32_t aChunkSize = mHeaderParser.GiveHeader().ChunkSize();
 
-    aChunkSize += aChunkSize % 2;
-
     if (aChunkName == FRMT_CODE) {
       if (!FmtChunkParserInit()) {
         return false;
@@ -135,7 +133,8 @@ WAVTrackDemuxer::Init()
       }
       break;
     } else {
-      mOffset += aChunkSize; // Skip other irrelevant chunks.
+      // Wave files are 2-byte aligned so we need to round up
+      mOffset += (aChunkSize + 1) & ~1; // Skip other irrelevant chunks.
     }
     mHeaderParser.Reset();
   }