diff --git a/overviewer_core/src/overviewer.h b/overviewer_core/src/overviewer.h
index b9751f2..c5c416c 100644
--- a/overviewer_core/src/overviewer.h
+++ b/overviewer_core/src/overviewer.h
@@ -26,7 +26,7 @@
 
 // increment this value if you've made a change to the c extesion
 // and want to force users to rebuild
-#define OVERVIEWER_EXTENSION_VERSION 14
+#define OVERVIEWER_EXTENSION_VERSION 15
 
 /* Python PIL, and numpy headers */
 #include <Python.h>
diff --git a/overviewer_core/src/primitives/cave.c b/overviewer_core/src/primitives/cave.c
index 82da455..6cd6453 100644
--- a/overviewer_core/src/primitives/cave.c
+++ b/overviewer_core/src/primitives/cave.c
@@ -103,7 +103,7 @@ cave_occluded(void *data, RenderState *state, int x, int y, int z) {
 
     if (z != 127) {
         if ( (x == 0) && (y != 15) ) {
-            if (state->left_blocks != Py_None) {
+            if (state->left_blocks != NULL) {
                 if (!is_transparent(getArrayByte3D(state->left_blocks, 15, y, z)) &&
                     !is_transparent(getArrayByte3D(state->blocks, x, y, z+1)) &&
                     !is_transparent(getArrayByte3D(state->blocks, x, y+1, z))) {
@@ -115,7 +115,7 @@ cave_occluded(void *data, RenderState *state, int x, int y, int z) {
         }
     
         if ( (x != 0) && (y == 15) ) {
-            if (state->right_blocks != Py_None) {
+            if (state->right_blocks != NULL) {
                 if (!is_transparent(getArrayByte3D(state->blocks, x-1, y, z)) &&
                     !is_transparent(getArrayByte3D(state->right_blocks, x, 0, z)) &&
                     !is_transparent(getArrayByte3D(state->blocks, x, y, z+1))) {
@@ -127,8 +127,8 @@ cave_occluded(void *data, RenderState *state, int x, int y, int z) {
         }
     
         if ( (x == 0) && (y == 15) ) {
-            if ((state->left_blocks != Py_None) &&
-                (state->right_blocks != Py_None)) {
+            if ((state->left_blocks != NULL) &&
+                (state->right_blocks != NULL)) {
                 if (!is_transparent(getArrayByte3D(state->left_blocks, 15, y, z)) &&
                     !is_transparent(getArrayByte3D(state->right_blocks, x, 0, z)) &&
                     !is_transparent(getArrayByte3D(state->blocks, x, y, z+1))) {
diff --git a/overviewer_core/src/primitives/edge-lines.c b/overviewer_core/src/primitives/edge-lines.c
index f1e4e42..f30d2a6 100644
--- a/overviewer_core/src/primitives/edge-lines.c
+++ b/overviewer_core/src/primitives/edge-lines.c
@@ -45,7 +45,7 @@ edge_lines_draw(void *data, RenderState *state, PyObject *src, PyObject *mask, P
         else if ((state->block == 78) || (state->block == 93) || (state->block == 94)) // snow, redstone repeaters (on and off)
             increment=9;
 
-        if ((state->x == 15) && (state->up_right_blocks != Py_None)) {
+        if ((state->x == 15) && (state->up_right_blocks != NULL)) {
             unsigned char side_block = getArrayByte3D(state->up_right_blocks, 0, state->y, state->z);
             if (side_block != state->block && is_transparent(side_block)) {
                 ImagingDrawLine(img_i, state->imgx+12, state->imgy+1+increment, state->imgx+22+1, state->imgy+5+1+increment, &ink, 1);
@@ -61,7 +61,7 @@ edge_lines_draw(void *data, RenderState *state, PyObject *src, PyObject *mask, P
         // if y != 0 and blocks[x,y-1,z] == 0
 
         // chunk boundries are annoying
-        if ((state->y == 0) && (state->up_left_blocks != Py_None)) {
+        if ((state->y == 0) && (state->up_left_blocks != NULL)) {
             unsigned char side_block = getArrayByte3D(state->up_left_blocks, state->x, 15, state->z);
             if (side_block != state->block && is_transparent(side_block)) {
                 ImagingDrawLine(img_i, state->imgx, state->imgy+6+1+increment, state->imgx+12+1, state->imgy+1+increment, &ink, 1);
diff --git a/overviewer_core/src/primitives/lighting.c b/overviewer_core/src/primitives/lighting.c
index 2d3e05d..7509578 100644
--- a/overviewer_core/src/primitives/lighting.c
+++ b/overviewer_core/src/primitives/lighting.c
@@ -133,8 +133,8 @@ estimate_blocklevel(RenderPrimitiveLighting *self, RenderState *state,
     }
 
     /* also, make sure we have enough info to correctly calculate lighting */
-    if (blocks == Py_None || blocks == NULL ||
-        blocklight == Py_None || blocklight == NULL) {
+    if (blocks == NULL ||
+        blocklight == NULL) {
         
         return 0;
     }
@@ -294,7 +294,7 @@ lighting_is_face_occluded(RenderState *state, int skip_sides, int x, int y, int
             /* this face isn't visible, so don't draw anything */
             return 1;
         }
-    } else if (skip_sides && (x == -1) && (state->left_blocks != Py_None)) {
+    } else if (skip_sides && (x == -1) && (state->left_blocks != NULL)) {
         unsigned char block = getArrayByte3D(state->left_blocks, 15, state->y, state->z);
         if (!is_transparent(block)) {
             /* the same thing but for adjacent chunks, this solves an
@@ -303,7 +303,7 @@ lighting_is_face_occluded(RenderState *state, int skip_sides, int x, int y, int
                tessellate-able */
                return 1;
            }
-    } else if (skip_sides && (y == 16) && (state->right_blocks != Py_None)) {
+    } else if (skip_sides && (y == 16) && (state->right_blocks != NULL)) {
         unsigned char block = getArrayByte3D(state->right_blocks, state->x, 0, state->z);
         if (!is_transparent(block)) {
             /* the same thing but for adjacent chunks, this solves an