diff --git a/panda/src/grutil/shaderTerrainMesh.I b/panda/src/grutil/shaderTerrainMesh.I
index f6a66bc7f5..f4a6b4286e 100644
--- a/panda/src/grutil/shaderTerrainMesh.I
+++ b/panda/src/grutil/shaderTerrainMesh.I
@@ -22,6 +22,7 @@
  * @param filename Heightfield texture
  */
 INLINE void ShaderTerrainMesh::set_heightfield(Texture* heightfield) {
+  MutexHolder holder(_lock);
   _heightfield_tex = heightfield;
 }
 
@@ -33,6 +34,7 @@ INLINE void ShaderTerrainMesh::set_heightfield(Texture* heightfield) {
  * @return Path to the heightfield
  */
 INLINE Texture* ShaderTerrainMesh::get_heightfield() const {
+  MutexHolder holder(_lock);
   return _heightfield_tex;
 }
 
@@ -54,6 +56,7 @@ INLINE Texture* ShaderTerrainMesh::get_heightfield() const {
  * @param chunk_size Size of the chunks, has to be a power of two
  */
 INLINE void ShaderTerrainMesh::set_chunk_size(size_t chunk_size) {
+  MutexHolder holder(_lock);
   _chunk_size = chunk_size;
 }
 
@@ -63,6 +66,7 @@ INLINE void ShaderTerrainMesh::set_chunk_size(size_t chunk_size) {
  * @return Chunk size
  */
 INLINE size_t ShaderTerrainMesh::get_chunk_size() const {
+  MutexHolder holder(_lock);
   return _chunk_size;
 }
 
@@ -81,6 +85,7 @@ INLINE size_t ShaderTerrainMesh::get_chunk_size() const {
  * @param generate_patches [description]
  */
 INLINE void ShaderTerrainMesh::set_generate_patches(bool generate_patches) {
+  MutexHolder holder(_lock);
   _generate_patches = generate_patches;
 }
 
@@ -92,6 +97,7 @@ INLINE void ShaderTerrainMesh::set_generate_patches(bool generate_patches) {
  * @return Whether to generate patches
  */
 INLINE bool ShaderTerrainMesh::get_generate_patches() const {
+  MutexHolder holder(_lock);
   return _generate_patches;
 }
 
@@ -107,6 +113,7 @@ INLINE bool ShaderTerrainMesh::get_generate_patches() const {
  * @param target_triangle_width Desired triangle width in pixels
  */
 INLINE void ShaderTerrainMesh::set_target_triangle_width(PN_stdfloat target_triangle_width) {
+  MutexHolder holder(_lock);
   _target_triangle_width = target_triangle_width;
 }
 
@@ -118,6 +125,7 @@ INLINE void ShaderTerrainMesh::set_target_triangle_width(PN_stdfloat target_tria
  * @return Target triangle width
  */
 INLINE PN_stdfloat ShaderTerrainMesh::get_target_triangle_width() const {
+  MutexHolder holder(_lock);
   return _target_triangle_width;
 }
 
@@ -131,6 +139,7 @@ INLINE PN_stdfloat ShaderTerrainMesh::get_target_triangle_width() const {
  * @param update_enabled Whether to update the terrain
  */
 INLINE void ShaderTerrainMesh::set_update_enabled(bool update_enabled) {
+  MutexHolder holder(_lock);
   _update_enabled = update_enabled;
 }
 
@@ -142,6 +151,7 @@ INLINE void ShaderTerrainMesh::set_update_enabled(bool update_enabled) {
  * @return Whether to update the terrain
  */
 INLINE bool ShaderTerrainMesh::get_update_enabled() const {
+  MutexHolder holder(_lock);
   return _update_enabled;
 }
 
diff --git a/panda/src/grutil/shaderTerrainMesh.cxx b/panda/src/grutil/shaderTerrainMesh.cxx
index 44c8397279..a0f3c34690 100644
--- a/panda/src/grutil/shaderTerrainMesh.cxx
+++ b/panda/src/grutil/shaderTerrainMesh.cxx
@@ -122,6 +122,7 @@ ShaderTerrainMesh::ShaderTerrainMesh() :
  * @return true if the terrain was initialized, false if an error occured
  */
 bool ShaderTerrainMesh::generate() {
+  MutexHolder holder(_lock);
   if (!do_check_heightfield())
     return false;
 
@@ -461,6 +462,7 @@ bool ShaderTerrainMesh::safe_to_combine() const {
  * @copydoc PandaNode::add_for_draw()
  */
 void ShaderTerrainMesh::add_for_draw(CullTraverser *trav, CullTraverserData &data) {
+  MutexHolder holder(_lock);
 
   // Make sure the terrain was properly initialized, and the geom was created
   // successfully
@@ -711,6 +713,7 @@ void ShaderTerrainMesh::do_emit_chunk(Chunk* chunk, TraversalData* data) {
  * @return World-Space point
  */
 LPoint3 ShaderTerrainMesh::uv_to_world(const LTexCoord& coord) const {
+  MutexHolder holder(_lock);
   nassertr(_heightfield_tex != nullptr, LPoint3(0)); // Heightfield not set yet
   nassertr(_heightfield_tex->has_ram_image(), LPoint3(0)); // Heightfield not in memory
 
diff --git a/panda/src/grutil/shaderTerrainMesh.h b/panda/src/grutil/shaderTerrainMesh.h
index c57a5d4e74..9c4f8d9a3a 100644
--- a/panda/src/grutil/shaderTerrainMesh.h
+++ b/panda/src/grutil/shaderTerrainMesh.h
@@ -25,6 +25,8 @@
 #include "configVariableInt.h"
 #include "pStatCollector.h"
 #include "filename.h"
+#include "pmutex.h"
+#include "mutexHolder.h"
 #include <stdint.h>
 
 extern ConfigVariableBool stm_use_hexagonal_layout;
@@ -160,6 +162,7 @@ private:
   void do_emit_chunk(Chunk* chunk, TraversalData* data);
   bool do_check_lod_matches(Chunk* chunk, TraversalData* data);
 
+  Mutex _lock;
   Chunk _base_chunk;
   size_t _size;
   size_t _chunk_size;