diff --git a/src/scripting/types.h b/src/scripting/types.h
index 7d2f2341c..e2d5f5f64 100644
--- a/src/scripting/types.h
+++ b/src/scripting/types.h
@@ -100,6 +100,7 @@ public:
 	VersionInfo		mVersion = { 0,0,0 };
 	uint8_t loadOp, storeOp, moveOp, RegType, RegCount;
 	EScopeFlags ScopeFlags = (EScopeFlags)0;
+	bool            SizeKnown = true;
 
 	PType(unsigned int size = 1, unsigned int align = 1);
 	virtual ~PType();
diff --git a/src/scripting/zscript/zcc_compile.cpp b/src/scripting/zscript/zcc_compile.cpp
index 51e819910..d4370578b 100644
--- a/src/scripting/zscript/zcc_compile.cpp
+++ b/src/scripting/zscript/zcc_compile.cpp
@@ -1492,8 +1492,12 @@ bool ZCCCompiler::CompileFields(PContainerType *type, TArray<ZCC_VarDeclarator *
 		auto name = field->Names;
 		do
 		{
-			if (fieldtype->Size == 0 && !(varflags & VARF_Native))	// Size not known yet.
+			if ((fieldtype->Size == 0 || !fieldtype->SizeKnown) && !(varflags & VARF_Native))	// Size not known yet.
 			{
+				if (type != nullptr)
+				{
+					type->SizeKnown = false;
+				}
 				return false;
 			}
 
@@ -1548,6 +1552,10 @@ bool ZCCCompiler::CompileFields(PContainerType *type, TArray<ZCC_VarDeclarator *
 
 							if (OutNamespace->Symbols.AddSymbol(f) == nullptr)
 							{ // name is already in use
+								if (type != nullptr)
+								{
+									type->SizeKnown = false;
+								}
 								f->Destroy();
 								return false;
 							}
@@ -1577,6 +1585,12 @@ bool ZCCCompiler::CompileFields(PContainerType *type, TArray<ZCC_VarDeclarator *
 		} while (name != field->Names);
 		Fields.Delete(0);
 	}
+
+	if (type != nullptr)
+	{
+		type->SizeKnown = Fields.Size() == 0;
+	}
+
 	return Fields.Size() == 0;
 }