diff --git a/flang/lib/Lower/IntrinsicCall.cpp b/flang/lib/Lower/IntrinsicCall.cpp
--- a/flang/lib/Lower/IntrinsicCall.cpp
+++ b/flang/lib/Lower/IntrinsicCall.cpp
@@ -3476,6 +3476,8 @@
                                                  remainder);
   }
   // Real case
+  if (resultType == mlir::FloatType::getF128(builder.getContext()))
+    TODO(loc, "MODULO intrinsic for 128 bit floats");
   auto remainder = builder.create<mlir::arith::RemFOp>(loc, args[0], args[1]);
   mlir::Value zero = builder.createRealZeroConstant(loc, remainder.getType());
   auto remainderIsNotZero = builder.create<mlir::arith::CmpFOp>(