diff --git a/lib/adts.cpp b/lib/adts.cpp
index 9756ff83..047c4010 100644
--- a/lib/adts.cpp
+++ b/lib/adts.cpp
@@ -12,7 +12,7 @@ namespace aac {
     len = 0;
   }
 
-  adts::adts(char * _data, unsigned long _len){
+  adts::adts(const char * _data, unsigned long _len){
     len = _len;
     data = (char*)malloc(len);
     memcpy(data, _data, len);
diff --git a/lib/adts.h b/lib/adts.h
index ce619c1b..8e759515 100644
--- a/lib/adts.h
+++ b/lib/adts.h
@@ -6,7 +6,7 @@ namespace aac {
   class adts {
     public:
       adts();
-      adts(char * _data, unsigned long _len);
+      adts(const char * _data, unsigned long _len);
       adts(const adts & rhs);
       ~adts();
       adts& operator = (const adts & rhs);