diff --git a/PVRTCEncoder/src/Block.cpp b/PVRTCEncoder/src/Block.cpp
index ab38131..5b49b3f 100644
--- a/PVRTCEncoder/src/Block.cpp
+++ b/PVRTCEncoder/src/Block.cpp
@@ -57,7 +57,7 @@
 
 namespace PVRTCC {
 
-  Block::Block(uint8 *data)
+  Block::Block(const uint8 *data)
     : m_ColorACached(false)
     , m_ColorBCached(false) {
     assert(data);
diff --git a/PVRTCEncoder/src/Block.h b/PVRTCEncoder/src/Block.h
index 76eb2c0..83dfe7f 100644
--- a/PVRTCEncoder/src/Block.h
+++ b/PVRTCEncoder/src/Block.h
@@ -61,7 +61,7 @@ namespace PVRTCC {
 
 class Block {
  public:
-  explicit Block(uint8 *data);
+  explicit Block(const uint8 *data);
 
   Pixel GetColorA();
   Pixel GetColorB();
diff --git a/PVRTCEncoder/src/Pixel.cpp b/PVRTCEncoder/src/Pixel.cpp
index f23a69d..e84b60e 100644
--- a/PVRTCEncoder/src/Pixel.cpp
+++ b/PVRTCEncoder/src/Pixel.cpp
@@ -130,7 +130,7 @@ namespace PVRTCC {
     return 0;
   }
 
-  void Pixel::ChangeBitDepth(uint8 (&depth)[4]) {
+  void Pixel::ChangeBitDepth(const uint8 (&depth)[4]) {
     for(uint32 i = 0; i < 4; i++) {
       m_Component[i] = ChangeBitDepth(m_Component[i], m_BitDepth[i], depth[i]);
       m_BitDepth[i] = depth[i];
diff --git a/PVRTCEncoder/src/Pixel.h b/PVRTCEncoder/src/Pixel.h
index 7dd2465..585af3f 100644
--- a/PVRTCEncoder/src/Pixel.h
+++ b/PVRTCEncoder/src/Pixel.h
@@ -80,7 +80,7 @@ class Pixel {
   // significant bits when going from larger to smaller bit depth
   // or by repeating the most significant bits when going from
   // smaller to larger bit depths.
-  void ChangeBitDepth(uint8 (&newDepth)[4]);
+  void ChangeBitDepth(const uint8 (&newDepth)[4]);
 
   // Changes the bit depth of a single component. See the comment
   // above for how we do this.