diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 4ffc9a6dad2..e7bb4fa3089 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -16737,12 +16737,14 @@ xref_tag (enum tag_types tag_code, tree name,
 	  if (CLASS_TYPE_P (t) && CLASSTYPE_IS_TEMPLATE (t))
 	    maybe_tmpl = CLASSTYPE_TI_TEMPLATE (t);
 
+	  /* FIXME: we should do a more precise check for redefinitions
+	     of a conflicting using-declaration here, as these diagnostics
+	     are not ideal.  */
 	  if (DECL_LANG_SPECIFIC (decl)
 	      && DECL_MODULE_IMPORT_P (decl)
-	      && TREE_CODE (CP_DECL_CONTEXT (decl)) == NAMESPACE_DECL)
+	      && CP_DECL_CONTEXT (decl) == current_namespace)
 	    {
 	      /* Push it into this TU's symbol slot.  */
-	      gcc_checking_assert (current_namespace == CP_DECL_CONTEXT (decl));
 	      if (maybe_tmpl != decl)
 		/* We're in the template parm binding level.
 		   Pushtag has logic to slide under that, but we're
diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
index e5f8562105e..361dc3d953d 100644
--- a/gcc/cp/name-lookup.cc
+++ b/gcc/cp/name-lookup.cc
@@ -3782,18 +3782,30 @@ check_module_override (tree decl, tree mvec, bool hiding,
 	  /* Errors could cause there to be nothing.  */
 	  continue;
 
+	tree type = NULL_TREE;
 	if (STAT_HACK_P (bind))
-	  /* We do not have to check STAT_TYPE here, the xref_tag
-	     machinery deals with that problem. */
-	  bind = STAT_VISIBLE (bind);
+	  {
+	    /* If there was a matching STAT_TYPE here then xref_tag
+	       should have found it, but we need to check anyway because
+	       a conflicting using-declaration may exist.  */
+	    if (STAT_TYPE_VISIBLE_P (bind))
+	      type = STAT_TYPE (bind);
+	    bind = STAT_VISIBLE (bind);
+	  }
 
-	for (ovl_iterator iter (bind); iter; ++iter)
-	  if (!iter.using_p ())
-	    {
-	      match = duplicate_decls (decl, *iter, hiding);
-	      if (match)
-		goto matched;
-	    }
+	if (type)
+	  {
+	    match = duplicate_decls (decl, strip_using_decl (type), hiding);
+	    if (match)
+	      goto matched;
+	  }
+
+	for (ovl_iterator iter (strip_using_decl (bind)); iter; ++iter)
+	  {
+	    match = duplicate_decls (decl, *iter, hiding);
+	    if (match)
+	      goto matched;
+	  }
       }
 
   if (TREE_PUBLIC (scope) && TREE_PUBLIC (STRIP_TEMPLATE (decl))
diff --git a/gcc/testsuite/g++.dg/modules/using-19_a.C b/gcc/testsuite/g++.dg/modules/using-19_a.C
new file mode 100644
index 00000000000..693a70ce7d4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-19_a.C
@@ -0,0 +1,18 @@
+// { dg-additional-options "-fmodules-ts -Wno-global-module" }
+// { dg-module-cmi M }
+
+module;
+
+namespace hidden {
+  struct S {};
+  enum E { e };
+  void f();
+}
+
+export module M;
+export namespace exposed {
+  using hidden::S;
+  using hidden::E;
+  using hidden::e;
+  using hidden::f;
+}
diff --git a/gcc/testsuite/g++.dg/modules/using-19_b.C b/gcc/testsuite/g++.dg/modules/using-19_b.C
new file mode 100644
index 00000000000..dbe8d9f3c01
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-19_b.C
@@ -0,0 +1,10 @@
+// { dg-additional-options "-fmodules-ts" }
+
+import M;
+
+namespace exposed {
+  struct S {};  // { dg-error "redefinition" }
+  enum E { x };  // { dg-error "multiple definition" }
+  int e();  // { dg-error "redeclared" }
+  int f;  // { dg-error "redeclared" }
+}