diff --git a/include/osg/Image b/include/osg/Image
index 6c94ae71b..5aeea2814 100644
--- a/include/osg/Image
+++ b/include/osg/Image
@@ -179,7 +179,7 @@ class SG_EXPORT Image : public Object
             return _data+(column*getPixelSizeInBits())/8+row*getRowSizeInBytes()+image*getImageSizeInBytes();
         }
         
-        inline unsigned char* data(int column, int row=0,int image=0) const
+        inline const unsigned char* data(int column, int row=0,int image=0) const
         {
             if (!_data) return NULL;
             return _data+(column*getPixelSizeInBits())/8+row*getRowSizeInBytes()+image*getImageSizeInBytes();
diff --git a/src/osg/Image.cpp b/src/osg/Image.cpp
index 65ee5edb8..38c017b78 100644
--- a/src/osg/Image.cpp
+++ b/src/osg/Image.cpp
@@ -885,7 +885,7 @@ bool Image::isImageTranslucent() const
     {
         for(int it=0;it<t();++it)
         {
-            unsigned char* d = data(0,it,ir);
+            const unsigned char* d = data(0,it,ir);
             switch(_dataType)
             {
                 case(GL_BYTE):              return _findLowerAlphaValueInRow(s(), (char*)d +offset,            (char)127, delta);