diff --git a/src/thingdef/thingdef_exp.cpp b/src/thingdef/thingdef_exp.cpp
index ffe7bf11a..991e9b947 100644
--- a/src/thingdef/thingdef_exp.cpp
+++ b/src/thingdef/thingdef_exp.cpp
@@ -112,7 +112,67 @@ static FxExpression *ParseExpressionM (FScanner &sc, PClassActor *cls)
 	}
 	else
 	{
-		return base;
+		FxBinary *exp;
+		FxAssignSelf *left = new FxAssignSelf(sc);
+
+		sc.GetToken();
+		switch (sc.TokenType)
+		{
+		case TK_AddEq:
+			exp = new FxAddSub('+', left, nullptr);
+			break;
+
+		case TK_SubEq:
+			exp = new FxAddSub('-', left, nullptr);
+			break;
+
+		case TK_MulEq:
+			exp = new FxMulDiv('*', left, nullptr);
+			break;
+
+		case TK_DivEq:
+			exp = new FxMulDiv('/', left, nullptr);
+			break;
+
+		case TK_ModEq:
+			exp = new FxMulDiv('%', left, nullptr);
+			break;
+
+		case TK_LShiftEq:
+			exp = new FxBinaryInt(TK_LShift, left, nullptr);
+			break;
+
+		case TK_RShiftEq:
+			exp = new FxBinaryInt(TK_RShift, left, nullptr);
+			break;
+
+		case TK_URShiftEq:
+			exp = new FxBinaryInt(TK_URShift, left, nullptr);
+			break;
+
+		case TK_AndEq:
+			exp = new FxBinaryInt('&', left, nullptr);
+			break;
+
+		case TK_XorEq:
+			exp = new FxBinaryInt('^', left, nullptr);
+			break;
+
+		case TK_OrEq:
+			exp = new FxBinaryInt('|', left, nullptr);
+			break;
+
+		default:
+			sc.UnGet();
+			delete left;
+			return base;
+		}
+
+		exp->right = ParseExpressionM(sc, cls);
+
+		FxAssign *ret = new FxAssign(base, exp);
+		left->Assignment = ret;
+		return ret;
 	}
 }
 
diff --git a/src/thingdef/thingdef_exp.h b/src/thingdef/thingdef_exp.h
index 1284f364d..7ec542772 100644
--- a/src/thingdef/thingdef_exp.h
+++ b/src/thingdef/thingdef_exp.h
@@ -527,6 +527,24 @@ public:
 	FxExpression *Resolve(FCompileContext&);
 	bool RequestAddress();
 	ExpEmit Emit(VMFunctionBuilder *build);
+
+	ExpEmit Address;
+};
+
+//==========================================================================
+//
+//	FxAssignSelf
+//
+//==========================================================================
+
+class FxAssignSelf : public FxExpression
+{
+public:
+	FxAssign *Assignment;
+
+	FxAssignSelf(const FScriptPosition &pos);
+	FxExpression *Resolve(FCompileContext&);
+	ExpEmit Emit(VMFunctionBuilder *build);
 };
 
 //==========================================================================
diff --git a/src/thingdef/thingdef_expression.cpp b/src/thingdef/thingdef_expression.cpp
index 34a2c0f95..07f4d9fdf 100644
--- a/src/thingdef/thingdef_expression.cpp
+++ b/src/thingdef/thingdef_expression.cpp
@@ -1077,10 +1077,11 @@ FxExpression *FxAssign::Resolve(FCompileContext &ctx)
 {
 	CHECKRESOLVED();
 	SAFE_RESOLVE(Base, ctx);
-	SAFE_RESOLVE(Right, ctx);
 
 	ValueType = Base->ValueType;
 
+	SAFE_RESOLVE(Right, ctx);
+
 	if (!Base->IsNumeric() || !Right->IsNumeric())
 	{
 		ScriptPosition.Message(MSG_ERROR, "Numeric type expected");
@@ -1120,8 +1121,10 @@ ExpEmit FxAssign::Emit(VMFunctionBuilder *build)
 	assert(ValueType->GetRegType() == Right->ValueType->GetRegType());
 
 	ExpEmit pointer = Base->Emit(build);
-	ExpEmit result = Right->Emit(build);
+	Address = pointer;
 
+	ExpEmit result = Right->Emit(build);
+	
 	if (result.Konst)
 	{
 		ExpEmit temp(build, result.RegType);
@@ -1142,6 +1145,39 @@ ExpEmit FxAssign::Emit(VMFunctionBuilder *build)
 	return result;
 }
 
+//==========================================================================
+//
+//	FxAssignSelf
+//
+//==========================================================================
+
+FxAssignSelf::FxAssignSelf(const FScriptPosition &pos)
+: FxExpression(pos)
+{
+	Assignment = nullptr;
+}
+
+FxExpression *FxAssignSelf::Resolve(FCompileContext &ctx)
+{
+	CHECKRESOLVED();
+
+	// This should never happen if FxAssignSelf is used correctly
+	assert(Assignment != nullptr);
+
+	ValueType = Assignment->ValueType;
+
+	return this;
+}
+
+ExpEmit FxAssignSelf::Emit(VMFunctionBuilder *build)
+{
+	assert(ValueType = Assignment->ValueType);
+	ExpEmit pointer = Assignment->Address; // FxAssign should have already emitted it
+	ExpEmit out(build, ValueType->GetRegType());
+	build->Emit(ValueType->GetLoadOp(), out.RegNum, pointer.RegNum, build->GetConstantInt(0));
+	return out;
+}
+
 //==========================================================================
 //
 //