diff --git a/src/playsim/p_actionfunctions.cpp b/src/playsim/p_actionfunctions.cpp
index 74faa78af2..ed8905b306 100644
--- a/src/playsim/p_actionfunctions.cpp
+++ b/src/playsim/p_actionfunctions.cpp
@@ -5123,6 +5123,11 @@ DEFINE_ACTION_FUNCTION(AActor, A_ChangeModel)
 
 	if (self == nullptr)
 		ACTION_RETURN_BOOL(false);
+	else if (modeldef != NAME_None && PClass::FindClass(modeldef.GetChars()) == nullptr)
+	{
+		Printf("Attempt to pass invalid modeldef name %s in %s.", modeldef.GetChars(), self->GetCharacterName());
+		ACTION_RETURN_BOOL(false);
+	}
 	else if (modelindex < 0)
 	{
 		Printf("Attempt to pass invalid model index %d in %s, index must be non-negative.", modelindex, self->GetCharacterName());