diff --git a/flang/lib/Optimizer/Dialect/FIRType.cpp b/flang/lib/Optimizer/Dialect/FIRType.cpp
--- a/flang/lib/Optimizer/Dialect/FIRType.cpp
+++ b/flang/lib/Optimizer/Dialect/FIRType.cpp
@@ -456,6 +456,8 @@
 mlir::LogicalResult
 fir::BoxType::verify(llvm::function_ref<mlir::InFlightDiagnostic()> emitError,
                      mlir::Type eleTy) {
+  if (eleTy.isa<fir::BaseBoxType>())
+    return emitError() << "invalid element type\n";
   // TODO
   return mlir::success();
 }
diff --git a/flang/test/Fir/invalid-types.fir b/flang/test/Fir/invalid-types.fir
--- a/flang/test/Fir/invalid-types.fir
+++ b/flang/test/Fir/invalid-types.fir
@@ -167,3 +167,8 @@
 
 // expected-error@+1 {{invalid element type}}
 func.func private @upe() -> !fir.class<!fir.box<i32>>
+
+// -----
+
+// expected-error@+1 {{invalid element type}}
+func.func private @upe() -> !fir.box<!fir.class<none>>