diff --git a/src/playsim/fragglescript/t_func.cpp b/src/playsim/fragglescript/t_func.cpp
index effbd5d3c00..c479e9015c9 100644
--- a/src/playsim/fragglescript/t_func.cpp
+++ b/src/playsim/fragglescript/t_func.cpp
@@ -1273,7 +1273,7 @@ void FParser::SF_MobjTarget(void)
 		}
 		
 		t_return.type = svt_mobj;
-		t_return.value.mobj = mo ? mo->target : NULL;
+		t_return.value.mobj = mo ? mo->target : nullptr;
 	}
 }
 
diff --git a/src/playsim/p_actionfunctions.cpp b/src/playsim/p_actionfunctions.cpp
index 1bcdfaea5b4..10d8abb9d89 100644
--- a/src/playsim/p_actionfunctions.cpp
+++ b/src/playsim/p_actionfunctions.cpp
@@ -1201,7 +1201,7 @@ DEFINE_ACTION_FUNCTION(AActor, A_CustomRailgun)
 	{
 		self->Angles.Yaw = self->AngleTo(self->target);
 	}
-	self->Angles.Pitch = P_AimLineAttack (self, self->Angles.Yaw, MISSILERANGE, &t, 60., 0, aim ? self->target : NULL);
+	self->Angles.Pitch = P_AimLineAttack (self, self->Angles.Yaw, MISSILERANGE, &t, 60., 0, aim ? self->target : nullptr);
 	if (t.linetarget == NULL && aim)
 	{
 		// We probably won't hit the target, but aim at it anyway so we don't look stupid.