diff --git a/crates/oxc_ast/src/ast/ts.rs b/crates/oxc_ast/src/ast/ts.rs
index 44ea9e67815ba..a0471d958728f 100644
--- a/crates/oxc_ast/src/ast/ts.rs
+++ b/crates/oxc_ast/src/ast/ts.rs
@@ -456,16 +456,6 @@ pub enum TSTypeOperatorOperator {
     Readonly = 2,
 }
 
-impl TSTypeOperatorOperator {
-    pub fn to_str(self) -> &'static str {
-        match self {
-            TSTypeOperatorOperator::Keyof => "keyof",
-            TSTypeOperatorOperator::Readonly => "readonly",
-            TSTypeOperatorOperator::Unique => "unique",
-        }
-    }
-}
-
 /// TypeScript Array Type
 ///
 /// Does not include tuple types, which are stored as [`TSTupleType`].
@@ -1372,20 +1362,6 @@ pub enum TSModuleDeclarationKind {
     Namespace = 2,
 }
 
-impl TSModuleDeclarationKind {
-    pub fn is_global(self) -> bool {
-        matches!(self, TSModuleDeclarationKind::Global)
-    }
-
-    pub fn to_str(self) -> &'static str {
-        match self {
-            TSModuleDeclarationKind::Global => "global",
-            TSModuleDeclarationKind::Namespace => "namespace",
-            TSModuleDeclarationKind::Module => "module",
-        }
-    }
-}
-
 /// The name of a TypeScript [namespace or module declaration](TSModuleDeclaration).
 ///
 /// Note that it is a syntax error for namespace declarations to have a string literal name.
@@ -1426,24 +1402,6 @@ pub enum TSModuleDeclarationBody<'a> {
     TSModuleBlock(Box<'a, TSModuleBlock<'a>>) = 1,
 }
 
-impl<'a> TSModuleDeclarationBody<'a> {
-    pub fn is_empty(&self) -> bool {
-        match self {
-            TSModuleDeclarationBody::TSModuleDeclaration(declaration) => declaration.body.is_none(),
-            TSModuleDeclarationBody::TSModuleBlock(block) => block.body.len() == 0,
-        }
-    }
-
-    pub fn as_module_block_mut(&mut self) -> Option<&mut TSModuleBlock<'a>> {
-        match self {
-            TSModuleDeclarationBody::TSModuleBlock(block) => Some(block.as_mut()),
-            TSModuleDeclarationBody::TSModuleDeclaration(decl) => {
-                decl.body.as_mut().and_then(|body| body.as_module_block_mut())
-            }
-        }
-    }
-}
-
 // See serializer in serialize.rs
 #[ast(visit)]
 #[derive(Debug)]
diff --git a/crates/oxc_ast/src/ast_impl/ts.rs b/crates/oxc_ast/src/ast_impl/ts.rs
index 624ccbcaa9037..c0b5755152432 100644
--- a/crates/oxc_ast/src/ast_impl/ts.rs
+++ b/crates/oxc_ast/src/ast_impl/ts.rs
@@ -173,7 +173,11 @@ impl<'a> TSModuleDeclaration<'a> {
 }
 
 impl TSModuleDeclarationKind {
-    pub fn as_str(&self) -> &str {
+    pub fn is_global(self) -> bool {
+        matches!(self, TSModuleDeclarationKind::Global)
+    }
+
+    pub fn as_str(&self) -> &'static str {
         match self {
             Self::Global => "global",
             Self::Module => "module",
@@ -208,6 +212,22 @@ impl<'a> TSModuleDeclarationBody<'a> {
     pub fn is_strict(&self) -> bool {
         matches!(self, Self::TSModuleBlock(block) if block.is_strict())
     }
+
+    pub fn is_empty(&self) -> bool {
+        match self {
+            TSModuleDeclarationBody::TSModuleDeclaration(declaration) => declaration.body.is_none(),
+            TSModuleDeclarationBody::TSModuleBlock(block) => block.body.len() == 0,
+        }
+    }
+
+    pub fn as_module_block_mut(&mut self) -> Option<&mut TSModuleBlock<'a>> {
+        match self {
+            TSModuleDeclarationBody::TSModuleBlock(block) => Some(block.as_mut()),
+            TSModuleDeclarationBody::TSModuleDeclaration(decl) => {
+                decl.body.as_mut().and_then(|body| body.as_module_block_mut())
+            }
+        }
+    }
 }
 
 impl<'a> TSModuleBlock<'a> {
@@ -255,3 +275,13 @@ impl ImportOrExportKind {
         matches!(self, Self::Type)
     }
 }
+
+impl TSTypeOperatorOperator {
+    pub fn to_str(self) -> &'static str {
+        match self {
+            TSTypeOperatorOperator::Keyof => "keyof",
+            TSTypeOperatorOperator::Readonly => "readonly",
+            TSTypeOperatorOperator::Unique => "unique",
+        }
+    }
+}
diff --git a/crates/oxc_prettier/src/format/mod.rs b/crates/oxc_prettier/src/format/mod.rs
index 4b8d744eed93b..b50e8360f2209 100644
--- a/crates/oxc_prettier/src/format/mod.rs
+++ b/crates/oxc_prettier/src/format/mod.rs
@@ -1272,7 +1272,7 @@ impl<'a> Format<'a> for TSModuleDeclaration<'a> {
             parts.push(ss!("declare "));
         }
 
-        parts.push(ss!(self.kind.to_str()));
+        parts.push(ss!(self.kind.as_str()));
         parts.push(space!());
         parts.push(self.id.format(p));
         parts.push(ss!(" {"));