diff --git a/panda/src/pipeline/mutexDebug.h b/panda/src/pipeline/mutexDebug.h
index 5689ff7fe9..43ae619273 100644
--- a/panda/src/pipeline/mutexDebug.h
+++ b/panda/src/pipeline/mutexDebug.h
@@ -22,8 +22,7 @@
 #include "pandabase.h"
 #include "mutexImpl.h"
 #include "conditionVarImpl.h"
-
-class Thread;
+#include "thread.h"
 
 #ifdef DEBUG_THREADS