diff --git a/Include/internal/pycore_optimizer_types.h b/Include/internal/pycore_optimizer_types.h
index 0a193268c4d618..10828d1027dd09 100644
--- a/Include/internal/pycore_optimizer_types.h
+++ b/Include/internal/pycore_optimizer_types.h
@@ -8,6 +8,7 @@ extern "C" {
 #  error "this header requires Py_BUILD_CORE define"
 #endif
 
+#include <stdbool.h>
 #include "pycore_uop.h"  // UOP_MAX_TRACE_LENGTH
 
 // Holds locals, stack, locals, stack ... (in that order)