diff --git a/flang/lib/Semantics/check-call.cpp b/flang/lib/Semantics/check-call.cpp
--- a/flang/lib/Semantics/check-call.cpp
+++ b/flang/lib/Semantics/check-call.cpp
@@ -574,6 +574,13 @@
         "Actual argument associated with %s may not be null pointer %s"_err_en_US,
         dummyName, actual.AsFortran());
   }
+
+  // checks for attributes that are known to be unimplemented 
+  if (dummyIsVolatile) {
+    messages.Say(
+        "VOLATILE keyword is not yet supported so this may lead to undefined behavior %s"_warn_en_US,
+        dummyName);
+  }
 }
 
 static void CheckProcedureArg(evaluate::ActualArgument &arg,