diff --git a/Source/MaterialDef.cs b/Source/MaterialDef.cs
index 0745ea9..8a9c314 100644
--- a/Source/MaterialDef.cs
+++ b/Source/MaterialDef.cs
@@ -43,9 +43,10 @@ public static void Load()
 
 		foreach (var node in GameDatabase.Instance.GetConfigNodes("SHABBY_MATERIAL_DEF")) {
 			var def = new MaterialDef(node);
-			if (string.IsNullOrEmpty(def.name)) {
-				Debug.LogError("[Shabby] material definition must have a valid name");
-			} else {
+			if (string.IsNullOrEmpty(def.name) || !def.isValid) {
+				Debug.LogError($"[Shabby][MaterialDef {def.name}] removing invalid definition");
+			}
+			else {
 				items[def.name] = def;
 			}
 		}
diff --git a/Source/MaterialReplacement.cs b/Source/MaterialReplacement.cs
index 897087c..3cbb9a5 100644
--- a/Source/MaterialReplacement.cs
+++ b/Source/MaterialReplacement.cs
@@ -65,7 +65,7 @@ static void Postfix(ref GameObject __result, ConfigNode partCfg)
 		foreach (ConfigNode node in partCfg.nodes) {
 			if (node.name != replacementNodeName) continue;
 			var replacement = new MaterialReplacement(node);
-			if (replacement.materialDef?.isValid == true) replacements.Add(replacement);
+			if (replacement.materialDef != null) replacements.Add(replacement);
 		}
 
 		// Apply blanket replacements or material name replacements.