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
@@ -719,7 +719,8 @@
       if (actual) {
         CheckExplicitInterfaceArg(
             *actual, dummy, proc, localContext, scope, intrinsic);
-      } else if (!dummy.IsOptional()) {
+      } else if (!dummy.IsOptional() &&
+          !std::holds_alternative<characteristics::AlternateReturn>(dummy.u)) {
         if (dummy.name.empty()) {
           messages.Say(
               "Dummy argument #%d is not OPTIONAL and is not associated with "
diff --git a/flang/test/Semantics/altreturn06.f90 b/flang/test/Semantics/altreturn06.f90
new file mode 100644
--- /dev/null
+++ b/flang/test/Semantics/altreturn06.f90
@@ -0,0 +1,11 @@
+! RUN: %S/test_errors.sh %s %t %f18
+! Test argument passing for internal and external subprograms
+! Both of the following are OK
+  call extSubprogram (*100)
+  call intSubprogram (*100)
+100 PRINT *,'First alternate return'
+contains
+  subroutine intSubprogram(*)
+    return(1)
+  end subroutine
+end