diff --git a/direct/src/interval/config_interval.h b/direct/src/interval/config_interval.h
index 39703ba38b..4f48b44875 100644
--- a/direct/src/interval/config_interval.h
+++ b/direct/src/interval/config_interval.h
@@ -28,7 +28,7 @@
 NotifyCategoryDecl(interval, EXPCL_DIRECT, EXPTP_DIRECT);
 
 extern ConfigVariableDouble interval_precision;
-extern ConfigVariableBool verify_intervals;
+extern EXPCL_DIRECT ConfigVariableBool verify_intervals;
 
 extern EXPCL_DIRECT void init_libinterval();