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
@@ -482,7 +482,8 @@
 
 std::string getTypeAsString(mlir::Type ty, const fir::KindMapping &kindMap,
                             llvm::StringRef prefix) {
-  std::stringstream name;
+  std::string buf;
+  llvm::raw_string_ostream name{buf};
   name << prefix.str();
   if (!prefix.empty())
     name << "_";
@@ -535,8 +536,10 @@
     } else if (auto boxTy = mlir::dyn_cast_or_null<fir::BoxType>(ty)) {
       name << "box_";
       ty = boxTy.getEleTy();
+    } else if (auto recTy = mlir::dyn_cast_or_null<fir::RecordType>(ty)) {
+      name << "rec_" << recTy.getName();
+      break;
     } else {
-      // TODO: add support for RecordType
       llvm::report_fatal_error("unsupported type");
     }
   }
diff --git a/flang/unittests/Optimizer/FIRTypesTest.cpp b/flang/unittests/Optimizer/FIRTypesTest.cpp
--- a/flang/unittests/Optimizer/FIRTypesTest.cpp
+++ b/flang/unittests/Optimizer/FIRTypesTest.cpp
@@ -299,4 +299,9 @@
   EXPECT_EQ("class_none",
       fir::getTypeAsString(
           fir::ClassType::get(mlir::NoneType::get(&context)), *kindMap));
+  auto derivedTy = fir::RecordType::get(&context, "derived");
+  llvm::SmallVector<std::pair<std::string, mlir::Type>> components;
+  components.emplace_back("p1", mlir::IntegerType::get(&context, 64));
+  derivedTy.finalize({}, components);
+  EXPECT_EQ("rec_derived", fir::getTypeAsString(derivedTy, *kindMap));
 }