diff --git a/gcc/rust/backend/rust-mangle.cc b/gcc/rust/backend/rust-mangle.cc
index 7f09d46a6503..8d104846b847 100644
--- a/gcc/rust/backend/rust-mangle.cc
+++ b/gcc/rust/backend/rust-mangle.cc
@@ -351,6 +351,10 @@ v0_identifier (const std::string &identifier)
   // <undisambiguated-identifier>, right under the <identifier> one. If the
   // identifier contains unicode values, then an extra "u" needs to be added to
   // the mangling string and `punycode` must be used to encode the characters.
+
+  if (!is_ascii_only (identifier))
+    mangled << "u";
+
   tl::optional<Utf8String> uident_opt
     = Utf8String::make_utf8_string (identifier);
   rust_assert (uident_opt.has_value ());
@@ -358,28 +362,19 @@ v0_identifier (const std::string &identifier)
     = encode_punycode (uident_opt.value ());
   rust_assert (punycode_opt.has_value ());
 
-  bool is_ascii_ident = true;
-  for (auto c : uident_opt.value ().get_chars ())
-    if (c.value > 127)
-      {
-	is_ascii_ident = false;
-	break;
-      }
-
   std::string punycode = punycode_opt.value ();
-  // remove tailing hyphen
+
+  // remove a tailing hyphen
   if (punycode.back () == '-')
     punycode.pop_back ();
-  // replace hyphens in punycode with underscores
-  std::replace (punycode.begin (), punycode.end (), '-', '_');
 
-  if (!is_ascii_ident)
-    mangled << "u";
+  // replace a hyphen in punycode with a underscore
+  std::replace (punycode.begin (), punycode.end (), '-', '_');
 
   mangled << std::to_string (punycode.size ());
-  // If the first character of the identifier is a digit or an underscore, we
-  // add an extra underscore
-  if (punycode[0] == '_')
+
+  // Add extra '_'
+  if (punycode[0] == '_' || ('0' <= punycode[0] && punycode[0] <= '9'))
     mangled << "_";
 
   mangled << punycode;
@@ -417,11 +412,11 @@ v0_function_path (V0Path path, Rust::Compile::Context *ctx,
 }
 
 static V0Path
-v0_scope_path (V0Path path, std::string ident)
+v0_scope_path (V0Path path, std::string ident, std::string ns)
 {
   V0Path v0path;
   v0path.prefix = "N";
-  v0path.ns = "v";
+  v0path.ns = ns;
   v0path.path = path.as_string ();
   v0path.ident = ident;
   return v0path;
@@ -507,7 +502,7 @@ v0_path (Rust::Compile::Context *ctx, const TyTy::BaseType *ty,
 	    }
 	    break;
 	  case HIR::ImplItem::CONSTANT:
-	    v0path = v0_scope_path (v0path, v0_identifier (seg.get ()));
+	    v0path = v0_scope_path (v0path, v0_identifier (seg.get ()), "v");
 	    break;
 	  default:
 	    rust_internal_error_at (UNDEF_LOCATION, "Attempt to mangle '%s'",
@@ -526,7 +521,7 @@ v0_path (Rust::Compile::Context *ctx, const TyTy::BaseType *ty,
 	    }
 	    break;
 	  case HIR::TraitItem::CONST:
-	    v0path = v0_scope_path (v0path, v0_identifier (seg.get ()));
+	    v0path = v0_scope_path (v0path, v0_identifier (seg.get ()), "v");
 	    break;
 	  default:
 	    rust_internal_error_at (UNDEF_LOCATION, "Attempt to mangle '%s'",
@@ -544,10 +539,12 @@ v0_path (Rust::Compile::Context *ctx, const TyTy::BaseType *ty,
 	  }
 	  break;
 	case HIR::Item::ItemKind::Module:
-	case HIR::Item::ItemKind::Trait:
+	  v0path = v0_scope_path (v0path, v0_identifier (seg.get ()), "t");
+	  break;
+	case HIR::Item::ItemKind::Trait: // FIXME: correct?
 	case HIR::Item::ItemKind::Static:
 	case HIR::Item::ItemKind::Constant:
-	  v0path = v0_scope_path (v0path, v0_identifier (seg.get ()));
+	  v0path = v0_scope_path (v0path, v0_identifier (seg.get ()), "v");
 	  break;
 	case HIR::Item::ItemKind::Struct:
 	case HIR::Item::ItemKind::Enum:
diff --git a/gcc/testsuite/rust/compile/v0-mangle1.rs b/gcc/testsuite/rust/compile/v0-mangle1.rs
new file mode 100644
index 000000000000..a34f1a70112a
--- /dev/null
+++ b/gcc/testsuite/rust/compile/v0-mangle1.rs
@@ -0,0 +1,70 @@
+// { dg-additional-options -frust-mangling=v0 }
+#[lang = "sized"]
+pub trait Sized {}
+
+pub fn foo() {}
+
+pub mod module_a {
+    pub fn bar() {}
+
+    pub mod module_b {
+        pub fn baz() {}
+    }
+}
+
+struct S; // { dg-warning "struct is never constructed" }
+
+// name starting with underscore.
+pub fn _uc() {}
+
+pub fn generic1<T>() {}
+
+pub fn generic2<T, U, V>() {}
+
+pub fn 初音ミク() {}
+
+pub fn іржа() {}
+
+pub fn あ1() {}
+
+fn main() {
+    // { dg-final { scan-assembler "_R.*NvC.*10v0_mangle13foo" } }
+    // cf. rustc 1.72.0: _RNvCshIBIgX6Bzox_10v0_mangle13foo
+    foo();
+
+    // { dg-final { scan-assembler "_R.*NvNtC.*10v0_mangle18module_a3bar" } }
+    // cf. rustc 1.72.0: _RNvNtCshIBIgX6Bzox_10v0_mangle18module_a3bar
+    module_a::bar();
+
+    // { dg-final { scan-assembler "_R.*NvNtNtC10v0_mangle18module_a8module_b3baz" } }
+    // cf. rustc 1.72.0: _RNvNtNtCshIBIgX6Bzox_10v0_mangle18module_a8module_b3baz
+    module_a::module_b::baz();
+
+    // { dg-final { scan-assembler "_R.*NvC.*10v0_mangle13__uc" } }
+    // cf. rustc 1.72.0: _RNvCshIBIgX6Bzox_10v0_mangle13__uc
+    _uc();
+
+    // { dg-final { scan-assembler "_R.*INvC.*10v0_mangle18generic1lE.*" } }
+    // cf. rustc 1.72.0: _RINvCshIBIgX6Bzox_10v0_mangle18generic1lEB2_
+    generic1::<i32>();
+
+    // { dg-final { scan-assembler "_R.*INvC.*10v0_mangle18generic1NtC.*10v0_mangle11SE.*" } }
+    // cf. rustc 1.72.0: _RINvCshIBIgX6Bzox_10v0_mangle18generic1NtB2_1SEB2_
+    generic1::<S>();
+
+    // { dg-final { scan-assembler "_R.*INvC.*10v0_mangle18generic2hfjE.*" } }
+    // cf. rustc 1.72.0: _RINvCshIBIgX6Bzox_10v0_mangle18generic2hfjEB2_
+    generic2::<u8, f32, usize>();
+
+    // { dg-final { scan-assembler "_R.*NvC.*10v0_mangle1u13pck1ew32ihn2d" } }
+    // cf. rustc 1.72.0: _RNvCshIBIgX6Bzox_10v0_mangle1u13pck1ew32ihn2d
+    初音ミク();
+
+    // { dg-final { scan-assembler "_R.*NvC.*10v0_mangle1u8_80al3a6f" } }
+    // cf. rustc 1.72.0: _RNvCshIBIgX6Bzox_10v0_mangle1u8_80al3a6f
+    іржа();
+
+    // { dg-final { scan-assembler "_R.*NvC.*10v0_mangle1u5_1_w7t" } }
+    // cf. rustc 1.72.0: _RNvCshIBIgX6Bzox_10v0_mangle1u5_1_w7t
+    あ1();
+}