diff --git a/panda/src/putil/copyOnWritePointer.I b/panda/src/putil/copyOnWritePointer.I
index ae7ab4403b..a4dceb8e3d 100644
--- a/panda/src/putil/copyOnWritePointer.I
+++ b/panda/src/putil/copyOnWritePointer.I
@@ -85,7 +85,7 @@ INLINE CopyOnWritePointer::
   }
 }
 
-#ifndef HAVE_THREADS
+#ifndef COW_THREADED
 ////////////////////////////////////////////////////////////////////
 //     Function: CopyOnWritePointer::get_read_pointer
 //       Access: Public
@@ -100,9 +100,9 @@ INLINE const CopyOnWriteObject *CopyOnWritePointer::
 get_read_pointer() const {
   return _object;
 }
-#endif  // HAVE_THREADS
+#endif  // COW_THREADED
 
-#ifndef HAVE_THREADS
+#ifndef COW_THREADED
 ////////////////////////////////////////////////////////////////////
 //     Function: CopyOnWritePointer::get_write_pointer
 //       Access: Public
@@ -129,7 +129,7 @@ get_write_pointer() {
   }
   return _object;
 }
-#endif  // HAVE_THREADS
+#endif  // COW_THREADED
 
 ////////////////////////////////////////////////////////////////////
 //     Function: CopyOnWritePointer::get_unsafe_pointer
@@ -247,7 +247,7 @@ operator = (To *object) {
 #endif  // CPPPARSER
 
 #ifndef CPPPARSER
-#ifdef HAVE_THREADS
+#ifdef COW_THREADED
 ////////////////////////////////////////////////////////////////////
 //     Function: CopyOnWritePointerTo::get_read_pointer
 //       Access: Public
@@ -258,7 +258,7 @@ INLINE CPT(TYPENAME CopyOnWritePointerTo<T>::To) CopyOnWritePointerTo<T>::
 get_read_pointer() const {
   return (const To *)(CopyOnWritePointer::get_read_pointer().p());
 }
-#else  // HAVE_THREADS
+#else  // COW_THREADED
 ////////////////////////////////////////////////////////////////////
 //     Function: CopyOnWritePointerTo::get_read_pointer
 //       Access: Public
@@ -269,11 +269,11 @@ INLINE const TYPENAME CopyOnWritePointerTo<T>::To *CopyOnWritePointerTo<T>::
 get_read_pointer() const {
   return (const To *)CopyOnWritePointer::get_read_pointer();
 }
-#endif  // HAVE_THREADS
+#endif  // COW_THREADED
 #endif  // CPPPARSER
 
 #ifndef CPPPARSER
-#ifdef HAVE_THREADS
+#ifdef COW_THREADED
 ////////////////////////////////////////////////////////////////////
 //     Function: CopyOnWritePointerTo::get_write_pointer
 //       Access: Public
@@ -284,7 +284,7 @@ INLINE PT(TYPENAME CopyOnWritePointerTo<T>::To) CopyOnWritePointerTo<T>::
 get_write_pointer() {
   return (To *)(CopyOnWritePointer::get_write_pointer().p());
 }
-#else  // HAVE_THREADS
+#else  // COW_THREADED
 ////////////////////////////////////////////////////////////////////
 //     Function: CopyOnWritePointerTo::get_write_pointer
 //       Access: Public
@@ -295,7 +295,7 @@ INLINE TYPENAME CopyOnWritePointerTo<T>::To *CopyOnWritePointerTo<T>::
 get_write_pointer() {
   return (To *)CopyOnWritePointer::get_write_pointer();
 }
-#endif  // HAVE_THREADS
+#endif  // COW_THREADED
 #endif  // CPPPARSER
 
 #ifndef CPPPARSER
diff --git a/panda/src/putil/copyOnWritePointer.cxx b/panda/src/putil/copyOnWritePointer.cxx
index e6980d6d90..52009ec079 100644
--- a/panda/src/putil/copyOnWritePointer.cxx
+++ b/panda/src/putil/copyOnWritePointer.cxx
@@ -21,7 +21,7 @@
 #include "config_util.h"
 #include "config_pipeline.h"
 
-#ifdef HAVE_THREADS
+#ifdef COW_THREADED
 ////////////////////////////////////////////////////////////////////
 //     Function: CopyOnWritePointer::get_read_pointer
 //       Access: Public
@@ -52,9 +52,9 @@ get_read_pointer() const {
   _object->_locking_thread = Thread::get_current_thread();
   return _object;
 }
-#endif  // HAVE_THREADS
+#endif  // COW_THREADED
 
-#ifdef HAVE_THREADS
+#ifdef COW_THREADED
 ////////////////////////////////////////////////////////////////////
 //     Function: CopyOnWritePointer::get_write_pointer
 //       Access: Public
@@ -125,4 +125,4 @@ get_write_pointer() {
 
   return _object;
 }
-#endif  // HAVE_THREADS
+#endif  // COW_THREADED
diff --git a/panda/src/putil/copyOnWritePointer.h b/panda/src/putil/copyOnWritePointer.h
index 1c0ca00749..39a794e853 100644
--- a/panda/src/putil/copyOnWritePointer.h
+++ b/panda/src/putil/copyOnWritePointer.h
@@ -25,6 +25,15 @@
 #include "pointerTo.h"
 #include "dcast.h"
 
+// Should we implement full thread protection for CopyOnWritePointer?
+// If we can be assured that no other thread will interrupt while a
+// write pointer is held, we don't need thread protection.
+#if defined(HAVE_THREADS) && !(defined(SIMPLE_THREADS) && defined(SIMPLE_THREADS_NO_IMPLICIT_YIELD))
+  #define COW_THREADED 1
+#else
+  #undef COW_THREADED
+#endif
+
 ////////////////////////////////////////////////////////////////////
 //       Class : CopyOnWritePointer
 // Description : This safely stores the primary, owned pointer to a
@@ -44,13 +53,13 @@ public:
   INLINE void operator = (CopyOnWriteObject *object);
   INLINE ~CopyOnWritePointer();
 
-#ifdef HAVE_THREADS
+#ifdef COW_THREADED
   CPT(CopyOnWriteObject) get_read_pointer() const;
   PT(CopyOnWriteObject) get_write_pointer();
 #else
   INLINE const CopyOnWriteObject *get_read_pointer() const;
   INLINE CopyOnWriteObject *get_write_pointer();
-#endif  // HAVE_THREADS
+#endif  // COW_THREADED
 
   INLINE CopyOnWriteObject *get_unsafe_pointer();
 
@@ -83,13 +92,13 @@ public:
   INLINE void operator = (const CopyOnWritePointerTo<T> &copy);
   INLINE void operator = (To *object);
 
-#ifdef HAVE_THREADS
+#ifdef COW_THREADED
   INLINE CPT(To) get_read_pointer() const;
   INLINE PT(To) get_write_pointer();
 #else
   INLINE const To *get_read_pointer() const;
   INLINE To *get_write_pointer();
-#endif  // HAVE_THREADS
+#endif  // COW_THREADED
 
   INLINE To *get_unsafe_pointer();
 #endif  // CPPPARSER