diff --git a/flang/runtime/allocatable.cpp b/flang/runtime/allocatable.cpp
--- a/flang/runtime/allocatable.cpp
+++ b/flang/runtime/allocatable.cpp
@@ -140,8 +140,15 @@
       descriptor, hasStat, errMsg, sourceFile, sourceLine)};
   if (stat == StatOk) {
     DescriptorAddendum *addendum{descriptor.Addendum()};
-    INTERNAL_CHECK(addendum != nullptr);
-    addendum->set_derivedType(derivedType);
+    if (addendum) { // Unlimited polymorphic allocated from intrinsic type spec
+                    // does not have
+      addendum->set_derivedType(derivedType);
+    } else {
+      // Unlimited polymorphic descriptors initialized with
+      // AllocatableInitIntrinsic do not have an addendum. Make sure the
+      // derivedType is null in that case.
+      INTERNAL_CHECK(!derivedType);
+    }
   }
   return stat;
 }
diff --git a/flang/runtime/pointer.cpp b/flang/runtime/pointer.cpp
--- a/flang/runtime/pointer.cpp
+++ b/flang/runtime/pointer.cpp
@@ -181,8 +181,14 @@
       pointer, hasStat, errMsg, sourceFile, sourceLine)};
   if (stat == StatOk) {
     DescriptorAddendum *addendum{pointer.Addendum()};
-    INTERNAL_CHECK(addendum != nullptr);
-    addendum->set_derivedType(derivedType);
+    if (addendum) {
+      addendum->set_derivedType(derivedType);
+    } else {
+      // Unlimited polymorphic descriptors initialized with
+      // PointerNullifyIntrinsic do not have an addendum. Make sure the
+      // derivedType is null in that case.
+      INTERNAL_CHECK(!derivedType);
+    }
   }
   return stat;
 }