diff --git a/Generator/Sources/SwiftWinRT/CommandLineArguments.swift b/Generator/Sources/SwiftWinRT/CommandLineArguments.swift
index 7500f24..51f35ef 100644
--- a/Generator/Sources/SwiftWinRT/CommandLineArguments.swift
+++ b/Generator/Sources/SwiftWinRT/CommandLineArguments.swift
@@ -28,8 +28,8 @@ struct CommandLineArguments: ParsableCommand {
     @Flag(name: .customLong("spm"), help: "Generate a package.swift file for building with SPM.")
     var generatePackageDotSwift: Bool = false
 
-    @Option(name: .customLong("support"), help: .init("The directory path or url:branch or url@revision of the support package to use.", valueName: "dir-or-url"))
-    var supportPackageLocation: String = "https://github.com/tristanlabelle/swift-winrt.git:main"
+    @Option(name: .customLong("spm-support-package"), help: .init("The directory path or '<url>#branch=<branch>' of the support package to reference.", valueName: "dir-or-url"))
+    var spmSupportPackageReference: String = "https://github.com/tristanlabelle/swift-winrt.git#branch=main"
 
     @Flag(name: .customLong("cmakelists"), help: "Generate a CMakeLists.txt files for building with CMake.")
     var generateCMakeLists: Bool = false
diff --git a/Generator/Sources/SwiftWinRT/Writing/SwiftPackageFile.swift b/Generator/Sources/SwiftWinRT/Writing/SwiftPackageFile.swift
index 3e6999c..a5da516 100644
--- a/Generator/Sources/SwiftWinRT/Writing/SwiftPackageFile.swift
+++ b/Generator/Sources/SwiftWinRT/Writing/SwiftPackageFile.swift
@@ -6,12 +6,12 @@ import struct Foundation.URL
 
 func writeSwiftPackageFile(
         _ projection: Projection,
-        supportPackageLocation: String,
+        supportPackageReference: String,
         excludeCMakeLists: Bool,
         dynamicLibraries: Bool,
         toPath path: String) {
     var package = SwiftPackage(name: "Projection")
-    package.dependencies.append(getSupportPackageDependency(location: supportPackageLocation))
+    package.dependencies.append(getSupportPackageDependency(reference: supportPackageReference))
 
     for module in projection.modulesByName.values {
         guard !module.isEmpty else { continue }
@@ -77,19 +77,26 @@ func writeSwiftPackageFile(
     package.write(version: "5.10", to: FileTextOutputStream(path: path, directoryCreation: .ancestors))
 }
 
-fileprivate func getSupportPackageDependency(location: String) -> SwiftPackage.Dependency {
-    if location.starts(with: "https://") {
-        if let separatorIndex = location.lastIndex(of: ":"),
-                let lastSlashIndex = location.lastIndex(of: "/"),
-                separatorIndex > lastSlashIndex {
-            let url = String(location[..<separatorIndex])
-            let branch = String(location[location.index(after: separatorIndex)...])
-            return .package(url: url, branch: branch)
+fileprivate func getSupportPackageDependency(reference: String) -> SwiftPackage.Dependency {
+    if reference.starts(with: "https://") {
+        guard let fragmentSeparatorIndex = reference.lastIndex(of: "#") else {
+            fatalError("Package URL reference should include # fragment: \(reference)")
         }
-        else {
-            fatalError("Unexpected support package location format: \(location)")
+
+        let url = reference[..<fragmentSeparatorIndex]
+        let fragment = reference[reference.index(after: fragmentSeparatorIndex)...]
+        guard let equalIndex = fragment.firstIndex(of: "=") else {
+            fatalError("Package URL fragment should include an assignment: \(reference)")
+        }
+
+        let lhs = fragment[..<equalIndex]
+        let rhs = fragment[fragment.index(after: equalIndex)...]
+        guard lhs == "branch" else {
+            fatalError("Package URL fragment should include a branch assignment: \(reference)")
         }
+
+        return .package(url: String(url), branch: String(rhs))
     } else {
-        return .package(name: "Support", path: location)
+        return .package(name: "Support", path: reference)
     }
 }
\ No newline at end of file
diff --git a/Generator/Sources/SwiftWinRT/main.swift b/Generator/Sources/SwiftWinRT/main.swift
index 9709700..71006f9 100644
--- a/Generator/Sources/SwiftWinRT/main.swift
+++ b/Generator/Sources/SwiftWinRT/main.swift
@@ -38,7 +38,7 @@ do {
     if commandLineArguments.generatePackageDotSwift {
         writeSwiftPackageFile(
             projection,
-            supportPackageLocation: commandLineArguments.supportPackageLocation,
+            supportPackageReference: commandLineArguments.spmSupportPackageReference,
             excludeCMakeLists: commandLineArguments.generateCMakeLists,
             dynamicLibraries: commandLineArguments.dynamicLibraries,
             toPath: "\(commandLineArguments.outputDirectoryPath)\\Package.swift")
diff --git a/InteropTests/Build-WinRTComponentProjection.ps1 b/InteropTests/Build-WinRTComponentProjection.ps1
index e61a4b4..22fed06 100644
--- a/InteropTests/Build-WinRTComponentProjection.ps1
+++ b/InteropTests/Build-WinRTComponentProjection.ps1
@@ -40,7 +40,7 @@ Write-Host -ForegroundColor Cyan "Generating Swift projection for WinRT componen
     -D "WINRTCOMPONENT_WINMD=$WinRTComponentBinDir\WinRTComponent.winmd" `
     -D "PROJECTION_JSON=$PSScriptRoot\projection.json" `
     -D "PROJECTION_DIR=$PSScriptRoot\Generated" `
-    -D "SPM_SUPPORT_MODULE_DIR=$PSScriptRoot\.." `
+    -D "SPM_SUPPORT_PACKAGE_DIR=$PSScriptRoot\.." `
     -P "$PSScriptRoot\GenerateProjection.cmake"
 
 Write-Host -ForegroundColor Cyan "Copying the WinRT component dll next to the test..."
diff --git a/InteropTests/CMakeLists.txt b/InteropTests/CMakeLists.txt
index 064c6f9..06ea06d 100644
--- a/InteropTests/CMakeLists.txt
+++ b/InteropTests/CMakeLists.txt
@@ -24,7 +24,7 @@ generate_projection(
     WINRTCOMPONENT_WINMD "${WINRTCOMPONENT_WINMD}"
     PROJECTION_JSON "${CMAKE_CURRENT_SOURCE_DIR}/projection.json"
     PROJECTION_DIR "${CMAKE_CURRENT_BINARY_DIR}/Projection/Sources"
-    SPM_SUPPORT_MODULE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/..")
+    SPM_SUPPORT_PACKAGE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/..")
 
 # Define WinRTComponent build (requires the cl.exe compiler)
 include(ExternalProject)
diff --git a/InteropTests/GenerateProjection.cmake b/InteropTests/GenerateProjection.cmake
index 4a323a8..ebffc44 100644
--- a/InteropTests/GenerateProjection.cmake
+++ b/InteropTests/GenerateProjection.cmake
@@ -1,7 +1,7 @@
 # Invokes SwiftWinRT to generate a Swift projection for a WinRT component
 # This file can be called as a CMake script.
 function(generate_projection)
-    cmake_parse_arguments("ARG" "" "SWIFTWINRT_EXE;WINRTCOMPONENT_WINMD;PROJECTION_JSON;PROJECTION_DIR;SPM_SUPPORT_MODULE_DIR" "" ${ARGN})
+    cmake_parse_arguments("ARG" "" "SWIFTWINRT_EXE;WINRTCOMPONENT_WINMD;PROJECTION_JSON;PROJECTION_DIR;SPM_SUPPORT_PACKAGE_DIR" "" ${ARGN})
 
     if ("${ARG_SWIFTWINRT_EXE}" STREQUAL "")
         message(FATAL_ERROR "SWIFTWINRT_EXE argument is required")
@@ -19,17 +19,17 @@ function(generate_projection)
         message(FATAL_ERROR "PROJECTION_DIR argument is required")
     endif()
 
-    if("${ARG_SPM_SUPPORT_MODULE_DIR}" STREQUAL "")
-        message(FATAL_ERROR "SPM_SUPPORT_MODULE_DIR argument is required")
+    if("${ARG_SPM_SUPPORT_PACKAGE_DIR}" STREQUAL "")
+        message(FATAL_ERROR "SPM_SUPPORT_PACKAGE_DIR argument is required")
     endif()
 
     # SPM won't handle an absolute path with a ".." component.
-    cmake_path(ABSOLUTE_PATH ARG_SPM_SUPPORT_MODULE_DIR NORMALIZE)
+    cmake_path(ABSOLUTE_PATH ARG_SPM_SUPPORT_PACKAGE_DIR NORMALIZE)
 
     cmake_path(CONVERT "${ARG_PROJECTION_JSON}" TO_NATIVE_PATH_LIST PROJECTION_JSON_NATIVE)
     string(REPLACE "\\" "" WINDOWS_SDK_VERSION "$ENV{WindowsSDKVersion}") # Remove trailing slash
     cmake_path(CONVERT "${ARG_WINRTCOMPONENT_WINMD}" TO_NATIVE_PATH_LIST WINRTCOMPONENT_WINMD_NATIVE)
-    cmake_path(CONVERT "${ARG_SPM_SUPPORT_MODULE_DIR}" TO_NATIVE_PATH_LIST SPM_SUPPORT_MODULE_DIR_NATIVE)
+    cmake_path(CONVERT "${ARG_SPM_SUPPORT_PACKAGE_DIR}" TO_NATIVE_PATH_LIST SPM_SUPPORT_PACKAGE_DIR_NATIVE)
     cmake_path(CONVERT "${ARG_PROJECTION_DIR}" TO_NATIVE_PATH_LIST PROJECTION_DIR_NATIVE)
     execute_process(
         COMMAND "${ARG_SWIFTWINRT_EXE}"
@@ -37,7 +37,7 @@ function(generate_projection)
             --winsdk "${WINDOWS_SDK_VERSION}"
             --reference "${WINRTCOMPONENT_WINMD_NATIVE}"
             --spm
-            --support "${SPM_SUPPORT_MODULE_DIR_NATIVE}"
+            --spm-support-package "${SPM_SUPPORT_PACKAGE_DIR_NATIVE}"
             --cmakelists
             --out "${PROJECTION_DIR_NATIVE}"
             --out-manifest "${PROJECTION_DIR_NATIVE}\\WinRTComponent.manifest"
@@ -51,5 +51,5 @@ if(CMAKE_SCRIPT_MODE_FILE AND NOT CMAKE_PARENT_LIST_FILE)
         WINRTCOMPONENT_WINMD "${WINRTCOMPONENT_WINMD}"
         PROJECTION_JSON "${PROJECTION_JSON}"
         PROJECTION_DIR "${PROJECTION_DIR}"
-        SPM_SUPPORT_MODULE_DIR "${SPM_SUPPORT_MODULE_DIR}")
+        SPM_SUPPORT_PACKAGE_DIR "${SPM_SUPPORT_PACKAGE_DIR}")
 endif()
\ No newline at end of file