diff --git a/lib/mp4.cpp b/lib/mp4.cpp
index 9f211a49..1a61349f 100644
--- a/lib/mp4.cpp
+++ b/lib/mp4.cpp
@@ -4191,7 +4191,7 @@ namespace MP4 {
     setDepth(0x0018);
   }
   
-  void VisualSampleEntry::setCodec(char* newCodec){
+  void VisualSampleEntry::setCodec(const char* newCodec){
     memcpy(data + 4, newCodec, 4);
   }
   
@@ -4304,7 +4304,7 @@ namespace MP4 {
     setSampleRate(44100);
   }
 
-  void AudioSampleEntry::setCodec(char* newCodec){
+  void AudioSampleEntry::setCodec(const char* newCodec){
     memcpy(data + 4, newCodec, 4);
   }
   
diff --git a/lib/mp4.h b/lib/mp4.h
index 2c39c91c..72320d32 100644
--- a/lib/mp4.h
+++ b/lib/mp4.h
@@ -819,7 +819,7 @@ namespace MP4 {
     ///\todo set default values
     public:
       VisualSampleEntry();
-      void setCodec(char* newCodec);
+      void setCodec(const char* newCodec);
       void setWidth(uint16_t newWidth);
       uint16_t getWidth();
       void setHeight(uint16_t newHeight);
@@ -844,7 +844,7 @@ namespace MP4 {
     public:
       ///\todo set default values
       AudioSampleEntry();
-      void setCodec(char* newCodec);
+      void setCodec(const char* newCodec);
       void setChannelCount(uint16_t newChannelCount);
       uint16_t getChannelCount();
       void setSampleSize(uint16_t newSampleSize);
diff --git a/lib/mp4_conv.cpp b/lib/mp4_conv.cpp
index 3cdbcba6..e9613ef2 100644
--- a/lib/mp4_conv.cpp
+++ b/lib/mp4_conv.cpp
@@ -48,7 +48,7 @@ namespace MP4{
       //putting all metadata in a huge vector 'keyParts'
       keyParts.clear();
       for (JSON::ObjIter trackIt = metaData["tracks"].ObjBegin(); trackIt != metaData["tracks"].ObjEnd(); trackIt++){
-        for (JSON::ObjArrIter keyIt = trackIt->second["keys"].ArrBegin(); keyIt != trackIt->second["keys"].ArrEnd(); keyIt++){
+        for (JSON::ArrIter keyIt = trackIt->second["keys"].ArrBegin(); keyIt != trackIt->second["keys"].ArrEnd(); keyIt++){
           keyPart temp;
           temp.trackID = trackIt->second["trackid"].asInt();
           temp.size = (*keyIt)["size"].asInt();