diff --git a/src/p_actionfunctions.cpp b/src/p_actionfunctions.cpp
index f5d7251c3..57c676801 100644
--- a/src/p_actionfunctions.cpp
+++ b/src/p_actionfunctions.cpp
@@ -4867,13 +4867,13 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_ChangeLinkFlags)
 
 	if (blockmap != -1)
 	{
-		if (blockmap == 0) self->flags &= *MF_NOBLOCKMAP;
+		if (blockmap == 0) self->flags &= ~MF_NOBLOCKMAP;
 		else self->flags |= MF_NOBLOCKMAP;
 	}
 
 	if (sector != -1)
 	{
-		if (sector == 0) self->flags &= *MF_NOSECTOR;
+		if (sector == 0) self->flags &= ~MF_NOSECTOR;
 		else self->flags |= MF_NOSECTOR;
 	}