diff --git a/.github/workflows/publish_release.yml b/.github/workflows/publish_release.yml
index 969181fc799..44f68cce276 100644
--- a/.github/workflows/publish_release.yml
+++ b/.github/workflows/publish_release.yml
@@ -11,7 +11,7 @@ on:
         required: true
       swift_syntax_version:
         type: string
-        default: 601.0.0
+        default: 603.0.0
         description: "swift-syntax version"
         # The version of swift-syntax to tag. If this is a prerelease, `-prerelease-<date>` is added to this version.
         required: true
diff --git a/BUILD.bazel b/BUILD.bazel
index 5a710ddeeb4..86301f4eec6 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -221,6 +221,7 @@ swift_syntax_library(
         ":SwiftSyntax600",
         ":SwiftSyntax601",
         ":SwiftSyntax602",
+        ":SwiftSyntax603",
         ":_SwiftSyntaxCShims",
     ],
 )
@@ -260,6 +261,13 @@ swift_syntax_library(
     ],
 )
 
+swift_syntax_library(
+    name = "SwiftSyntax603",
+    srcs = glob(["Sources/VersionMarkerModules/SwiftSyntax603/**/*.swift"]),
+    deps = [
+    ],
+)
+
 swift_syntax_library(
     name = "SwiftSyntaxBuilder",
     deps = [
diff --git a/Package.swift b/Package.swift
index 5c20ee04b86..844bfacc40a 100644
--- a/Package.swift
+++ b/Package.swift
@@ -212,6 +212,7 @@ let package = Package(
       name: "SwiftSyntax",
       dependencies: [
         "_SwiftSyntaxCShims", "SwiftSyntax509", "SwiftSyntax510", "SwiftSyntax600", "SwiftSyntax601", "SwiftSyntax602",
+        "SwiftSyntax603",
       ],
       exclude: ["CMakeLists.txt"],
       swiftSettings: swiftSyntaxSwiftSettings
@@ -250,6 +251,11 @@ let package = Package(
       path: "Sources/VersionMarkerModules/SwiftSyntax602"
     ),
 
+    .target(
+      name: "SwiftSyntax603",
+      path: "Sources/VersionMarkerModules/SwiftSyntax603"
+    ),
+
     // MARK: SwiftSyntaxBuilder
 
     .target(
diff --git a/Sources/VersionMarkerModules/CMakeLists.txt b/Sources/VersionMarkerModules/CMakeLists.txt
index 467d4aa2202..609f1d308d4 100644
--- a/Sources/VersionMarkerModules/CMakeLists.txt
+++ b/Sources/VersionMarkerModules/CMakeLists.txt
@@ -11,10 +11,12 @@
 add_library(${SWIFTSYNTAX_TARGET_NAMESPACE}SwiftSyntax509 STATIC
   SwiftSyntax509/Empty.swift)
 add_library(${SWIFTSYNTAX_TARGET_NAMESPACE}SwiftSyntax510 STATIC
-  SwiftSyntax509/Empty.swift)
+  SwiftSyntax510/Empty.swift)
 add_library(${SWIFTSYNTAX_TARGET_NAMESPACE}SwiftSyntax600 STATIC
-  SwiftSyntax509/Empty.swift)
+  SwiftSyntax600/Empty.swift)
 add_library(${SWIFTSYNTAX_TARGET_NAMESPACE}SwiftSyntax601 STATIC
-  SwiftSyntax509/Empty.swift)
+  SwiftSyntax601/Empty.swift)
 add_library(${SWIFTSYNTAX_TARGET_NAMESPACE}SwiftSyntax602 STATIC
-  SwiftSyntax509/Empty.swift)
\ No newline at end of file
+  SwiftSyntax602/Empty.swift)
+add_library(${SWIFTSYNTAX_TARGET_NAMESPACE}SwiftSyntax603 STATIC
+  SwiftSyntax603/Empty.swift)
diff --git a/Sources/VersionMarkerModules/SwiftSyntax603/Empty.swift b/Sources/VersionMarkerModules/SwiftSyntax603/Empty.swift
new file mode 100644
index 00000000000..cc2ffc3c32a
--- /dev/null
+++ b/Sources/VersionMarkerModules/SwiftSyntax603/Empty.swift
@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+// The SwiftSyntax603 module is intentionally empty.
+// It serves as an indicator which version of swift-syntax a package is building against.
+// See the 'Macro Versioning.md' document for more details.