diff --git a/include/osg/GL2Extensions b/include/osg/GL2Extensions
index d051a30e3..af46e7e73 100644
--- a/include/osg/GL2Extensions
+++ b/include/osg/GL2Extensions
@@ -552,6 +552,24 @@ typedef char GLchar;
 #define GL_TIMEOUT_IGNORED                0xFFFFFFFFFFFFFFFFull
 #endif
 
+#ifndef GL_TEXTURE_2D_ARRAY_EXT
+    #define GL_TEXTURE_2D_ARRAY_EXT           0x8C1A
+    #define GL_TEXTURE_2D_ARRAY_EXT                        0x8C1A
+    #define GL_PROXY_TEXTURE_2D_ARRAY_EXT                  0x8C1B
+    #define GL_TEXTURE_BINDING_2D_ARRAY_EXT                0x8C1D
+    #define GL_MAX_ARRAY_TEXTURE_LAYERS_EXT                0x88FF
+    #define GL_COMPARE_REF_DEPTH_TO_TEXTURE_EXT            0x884E
+    #define GL_SAMPLER_2D_ARRAY_EXT                        0x8DC1
+    #define GL_SAMPLER_2D_ARRAY_SHADOW_EXT                 0x8DC4
+    #define GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT    0x8CD4
+#endif
+
+#ifndef GL_MAX_3D_TEXTURE_SIZE
+    #define GL_MAX_3D_TEXTURE_SIZE      0x8073
+#endif
+
+typedef struct __GLsync *GLsync;
+
 // for compatibility with gl.h headers that don't support VBO,
 //GL_VERSION_1_5 and GL_ARB_vertex_buffer_object provide these types for OpenGL
 //all ES versions except GL_OES_VERSION_1_0 provide these types for OpenGL ES
diff --git a/include/osg/GraphicsContext b/include/osg/GraphicsContext
index 65ea3eae4..894c5d61a 100644
--- a/include/osg/GraphicsContext
+++ b/include/osg/GraphicsContext
@@ -541,8 +541,6 @@ public:
 
     virtual void swapBuffersImplementation(GraphicsContext* gc);
 
-    typedef struct __GLsync *GLsync;
-
     GLsync _previousSync;
 };
 
diff --git a/include/osg/Texture b/include/osg/Texture
index 2e898235d..2513f7ccd 100644
--- a/include/osg/Texture
+++ b/include/osg/Texture
@@ -188,17 +188,6 @@
     #define GL_TEXTURE_3D                     0x806F
 #endif
 
-#ifndef GL_TEXTURE_2D_ARRAY_EXT
-    #define GL_TEXTURE_2D_ARRAY_EXT           0x8C1A
-    #define GL_TEXTURE_2D_ARRAY_EXT                        0x8C1A
-    #define GL_PROXY_TEXTURE_2D_ARRAY_EXT                  0x8C1B
-    #define GL_TEXTURE_BINDING_2D_ARRAY_EXT                0x8C1D
-    #define GL_MAX_ARRAY_TEXTURE_LAYERS_EXT                0x88FF
-    #define GL_COMPARE_REF_DEPTH_TO_TEXTURE_EXT            0x884E
-    #define GL_SAMPLER_2D_ARRAY_EXT                        0x8DC1
-    #define GL_SAMPLER_2D_ARRAY_SHADOW_EXT                 0x8DC4
-    #define GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT    0x8CD4
-#endif
 
 #ifndef GL_TEXTURE_CUBE_MAP
     #define GL_TEXTURE_CUBE_MAP             0x8513
diff --git a/include/osg/Texture3D b/include/osg/Texture3D
index 391072154..b3d1d5d0a 100644
--- a/include/osg/Texture3D
+++ b/include/osg/Texture3D
@@ -16,10 +16,6 @@
 
 #include <osg/Texture>
 
-#ifndef GL_MAX_3D_TEXTURE_SIZE
-    #define GL_MAX_3D_TEXTURE_SIZE      0x8073
-#endif
-
 namespace osg {
 
 /** Encapsulates OpenGL 3D texture functionality. Doesn't support cube maps,
diff --git a/src/osg/Texture.cpp b/src/osg/Texture.cpp
index b759c35cf..a528095ad 100644
--- a/src/osg/Texture.cpp
+++ b/src/osg/Texture.cpp
@@ -2695,7 +2695,7 @@ Texture::GenerateMipmapMode Texture::mipmapBeforeTexImage(const State& state, bo
 #else
 
         const GL2Extensions* extensions = state.get<GL2Extensions>();
-        bool useGenerateMipMap = extensions->glGenerateMipmap;
+        bool useGenerateMipMap = extensions->glGenerateMipmap!=0;
 
         if (useGenerateMipMap)
         {