diff --git a/Source/C++/Core/Ap4HdlrAtom.cpp b/Source/C++/Core/Ap4HdlrAtom.cpp
index 42c117c54..e784ce668 100644
--- a/Source/C++/Core/Ap4HdlrAtom.cpp
+++ b/Source/C++/Core/Ap4HdlrAtom.cpp
@@ -89,7 +89,7 @@ AP4_HdlrAtom::AP4_HdlrAtom(AP4_UI32        size,
     // handle a special case: the Quicktime files have a pascal
     // string here, but ISO MP4 files have a C string.
     // we try to detect a pascal encoding and correct it.
-    if (name[0] == name_size-1) {
+    if ((AP4_UI08)name[0] == (AP4_UI08)(name_size-1)) {
         m_HandlerName = name+1;
     } else {
         m_HandlerName = name;
diff --git a/Source/C++/Core/Ap4StszAtom.cpp b/Source/C++/Core/Ap4StszAtom.cpp
index 2af9fecfe..cc4577a14 100644
--- a/Source/C++/Core/Ap4StszAtom.cpp
+++ b/Source/C++/Core/Ap4StszAtom.cpp
@@ -73,6 +73,13 @@ AP4_StszAtom::AP4_StszAtom(AP4_UI32        size,
     stream.ReadUI32(m_SampleSize);
     stream.ReadUI32(m_SampleCount);
     if (m_SampleSize == 0) { // means that the samples have different sizes
+        // check for overflow
+        if (m_SampleCount > (size-8)/4) {
+            m_SampleCount = 0;
+            return;
+        }
+        
+        // read the entries
         AP4_Cardinal sample_count = m_SampleCount;
         m_Entries.SetItemCount(sample_count);
         unsigned char* buffer = new unsigned char[sample_count*4];