diff --git a/mythtv/programs/mythcommflag/ClassicCommDetector.cpp b/mythtv/programs/mythcommflag/ClassicCommDetector.cpp
index 98304c7..1296a72 100644
--- a/mythtv/programs/mythcommflag/ClassicCommDetector.cpp
+++ b/mythtv/programs/mythcommflag/ClassicCommDetector.cpp
@@ -2042,7 +2042,7 @@ void ClassicCommDetector::BuildSceneChangeCommList(void)
 
     sceneCommBreakMap.clear();
 
-    memset(sc_histogram, 0, sizeof(sc_histogram));
+    memset(sc_histogram, 0, sizeof(*sc_histogram)*(seconds+1));
     for (uint64_t f = 1; f <= framesProcessed; f++)
     {
         if (sceneMap.contains(f))