diff --git a/Sources/CodableToTypeScript/Generator/PackageGenerator.swift b/Sources/CodableToTypeScript/Generator/PackageGenerator.swift
index 4a839d5..24f77e9 100644
--- a/Sources/CodableToTypeScript/Generator/PackageGenerator.swift
+++ b/Sources/CodableToTypeScript/Generator/PackageGenerator.swift
@@ -53,20 +53,17 @@ public final class PackageGenerator {
         )
 
         var symbolToSource: [String: SourceFile] = [:]
+        var convertedSources: [SourceFile: TSSourceFile] = [:]
 
         // collect symbols included in for each swift source file
         for module in context.modules.filter({ $0 !== context.swiftModule }) {
             for source in module.sources {
-                for type in source.types {
-                    guard
-                        let typeConverter = try? codeGenerator.converter(for: type.declaredInterfaceType),
-                        let declaredNames = try? typeConverter.decls().compactMap(\.declaredName)
-                    else {
-                        continue
-                    }
-                    for declaredName in declaredNames {
-                        symbolToSource[declaredName] = source
-                    }
+                guard let tsSource = try? codeGenerator.convert(source: source) else {
+                    continue
+                }
+                convertedSources[source] = tsSource
+                for declaredName in tsSource.memberDeclaredNames {
+                    symbolToSource[declaredName] = source
                 }
             }
         }
@@ -89,7 +86,7 @@ public final class PackageGenerator {
             while let source = targetSources.popLast() {
                 generatedSources.insert(source)
                 collect(at: source.file.lastPathComponent) {
-                    let tsSource = try codeGenerator.convert(source: source)
+                    let tsSource = try convertedSources[source] ?? (codeGenerator.convert(source: source))
 
                     let entry = PackageEntry(
                         file: try tsPath(module: source.module, file: source.file),
diff --git a/Tests/CodableToTypeScriptTests/PackageGeneratorTests.swift b/Tests/CodableToTypeScriptTests/PackageGeneratorTests.swift
index c658508..d7e86a7 100644
--- a/Tests/CodableToTypeScriptTests/PackageGeneratorTests.swift
+++ b/Tests/CodableToTypeScriptTests/PackageGeneratorTests.swift
@@ -106,4 +106,46 @@ final class PackageGeneratorTests: XCTestCase {
             return element.asDecl?.asType?.name == "D"
         }))
     }
+
+    func testCustomMappedTypeIngored() throws {
+        let context = Context()
+        let module = Reader(context: context).read(source: """
+        struct AbsoluteURL: Codable, RawRepresentable {
+            var rawValue: String
+
+            func encode(to encoder: any Encoder) throws {
+                var c = encoder.singleValueContainer()
+                try c.encode(rawValue)
+            }
+
+            init(from decoder: any Decoder) throws {
+                let c = try decoder.singleValueContainer()
+                self.rawValue = try c.decode(RawValue.self)
+            }
+        }
+        """, file: URL(fileURLWithPath: "A.swift")).module
+
+        let typeMap = TypeMap(mapFunction: { stype in
+            if stype.description == "AbsoluteURL" {
+                return .identity(name: "string")
+            }
+            return nil
+        })
+
+        let generator = PackageGenerator(
+            context: context,
+            typeConverterProvider: TypeConverterProvider(typeMap: typeMap),
+            symbols: SymbolTable(),
+            importFileExtension: .js,
+            outputDirectory: URL(fileURLWithPath: "/dev/null", isDirectory: true)
+        )
+        let result = try generator.generate(modules: [module])
+        XCTAssertEqual(result.entries.count, 1) // helper library only
+        let hasTSAbsoluteURL = result.entries.contains(where: { entry in
+            entry.source.memberDeclaredNames.contains(where: { name in
+                return name == "AbsoluteURL"
+            })
+        })
+        XCTAssertFalse(hasTSAbsoluteURL)
+    }
 }