diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5dfc7cd..34892ec 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,10 +17,18 @@ jobs:
   macos:
     name: macOS
     runs-on: macos-13
+    strategy:
+      matrix:
+        swift-syntax-version: ['509.0.0..<510.0.0', '510.0.0..<511.0.0']
+
     steps:
       - uses: actions/checkout@v4
       - name: Select Xcode 15
         run: sudo xcode-select -s /Applications/Xcode_15.0.app
+      - name: Set SWIFT_SYNTAX_VERSION environment variable
+        run: echo "SWIFT_SYNTAX_VERSION=${{ matrix.swift-syntax-version }}" >> $GITHUB_ENV
+      - name: Resolve Dependencies
+        run: swift package resolve
       - name: Run tests
         run: swift test
 
@@ -29,9 +37,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Install Swift
-        uses: slashmo/install-swift@v0.4.0
+        uses: swift-actions/setup-swift@v2
         with:
-          version: 5.9
+          swift-version: "5.10"
       - uses: actions/checkout@v4
       - name: Run tests
         run: swift test
diff --git a/Package.resolved b/Package.resolved
index ddf0806..0c7ecd1 100644
--- a/Package.resolved
+++ b/Package.resolved
@@ -5,17 +5,17 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/pointfreeco/swift-snapshot-testing",
       "state" : {
-        "revision" : "59b663f68e69f27a87b45de48cb63264b8194605",
-        "version" : "1.15.1"
+        "revision" : "625ccca8570773dd84a34ee51a81aa2bc5a4f97a",
+        "version" : "1.16.0"
       }
     },
     {
       "identity" : "swift-syntax",
       "kind" : "remoteSourceControl",
-      "location" : "https://github.com/apple/swift-syntax.git",
+      "location" : "https://github.com/apple/swift-syntax",
       "state" : {
-        "revision" : "6ad4ea24b01559dde0773e3d091f1b9e36175036",
-        "version" : "509.0.2"
+        "revision" : "fa8f95c2d536d6620cc2f504ebe8a6167c9fc2dd",
+        "version" : "510.0.1"
       }
     }
   ],
diff --git a/Package.swift b/Package.swift
index 2fcfe5e..45aef30 100644
--- a/Package.swift
+++ b/Package.swift
@@ -1,6 +1,7 @@
 // swift-tools-version: 5.9
 
 import CompilerPluginSupport
+import Foundation
 import PackageDescription
 
 let package = Package(
@@ -23,7 +24,13 @@ let package = Package(
   ],
   dependencies: [
     .package(url: "https://github.com/pointfreeco/swift-snapshot-testing", from: "1.15.0"),
-    .package(url: "https://github.com/apple/swift-syntax", from: "509.0.0"),
+    //.conditionalPackage(url: "https://github.com/apple/swift-syntax", envVar: "SWIFT_SYNTAX_VERSION", default: "509.0.0..<510.0.0")
+    //.conditionalPackage(url: "https://github.com/apple/swift-syntax", envVar: "SWIFT_SYNTAX_VERSION", default: "510.0.0..<511.0.0")
+    .conditionalPackage(
+      url: "https://github.com/apple/swift-syntax",
+      envVar: "SWIFT_SYNTAX_VERSION",
+      default: "509.0.0..<511.0.0"
+    ),
   ],
   targets: [
     .macro(
@@ -68,3 +75,55 @@ let package = Package(
     ),
   ]
 )
+
+extension Package.Dependency {
+  /// Creates a dependency based on an environment variable or a default version range.
+  ///
+  /// This function allows dynamically setting the version range of a package dependency via an environment variable.
+  /// If the environment variable is not set, it falls back to a specified default version range.
+  ///
+  /// - Parameters:
+  ///   - url: The URL of the package repository.
+  ///   - envVar: The name of the environment variable that contains the version range.
+  ///   - versionExpression: The default version range in case the environment variable is not set.
+  ///     Example format: `"509.0.0..<511.0.0"` or `"509.0.0...510.0.0"`.
+  /// - Returns: A `Package.Dependency` configured with the specified or default version range.
+  /// - Throws: A fatal error if the version expression format is invalid or the range operator is unsupported.
+  ///
+  static func conditionalPackage(
+    url: String,
+    envVar: String,
+    default versionExpression: String
+  ) -> Package.Dependency {
+    let versionRangeString = ProcessInfo.processInfo.environment[envVar] ?? versionExpression
+    let (lower, op, upper) = parseVersionExpression(from: versionRangeString)
+    if op == "..<" {
+      return .package(url: url, lower..<upper)
+    } else if op == "..." {
+      return .package(url: url, lower...upper)
+    } else {
+      fatalError("Unsupported version range operator: \(op)")
+    }
+  }
+
+  private static func parseVersionExpression(
+    from expression: String
+  ) -> (Version, String, Version) {
+    let rangeOperators = ["..<", "..."]
+    for op in rangeOperators {
+      if expression.contains(op) {
+        let parts = expression.split(separator: op, maxSplits: 1, omittingEmptySubsequences: true)
+          .map(String.init)
+        guard
+          parts.count == 2,
+          let lower = Version(parts[0]),
+          let upper = Version(parts[1])
+        else {
+          fatalError("Invalid version expression format: \(expression)")
+        }
+        return (lower, op, upper)
+      }
+    }
+    fatalError("No valid range operator found in expression: \(expression)")
+  }
+}
diff --git a/Sources/MemberwiseInitMacros/Macros/Support/ExprTypeInference.swift b/Sources/MemberwiseInitMacros/Macros/Support/ExprTypeInference.swift
index 240adbe..c8238bb 100644
--- a/Sources/MemberwiseInitMacros/Macros/Support/ExprTypeInference.swift
+++ b/Sources/MemberwiseInitMacros/Macros/Support/ExprTypeInference.swift
@@ -256,6 +256,11 @@ extension ExprSyntax {
       else { return nil }
       return .tuple(elementTypes)
 
+    #if canImport(SwiftSyntax510)
+      case .thenStmt:
+        return nil
+    #endif
+
     case .token, .accessorBlock, .accessorDeclList, .accessorDecl, .accessorEffectSpecifiers,
       .accessorParameters, .actorDecl, .arrayElementList, .arrayElement, .arrayType, .arrowExpr,
       .assignmentExpr, .associatedTypeDecl, .attributeList, .attribute, .attributedType,
diff --git a/Tests/MacroTestingTests/DictionaryStorageMacroTests.swift b/Tests/MacroTestingTests/DictionaryStorageMacroTests.swift
index b0bf67c..0b11b30 100644
--- a/Tests/MacroTestingTests/DictionaryStorageMacroTests.swift
+++ b/Tests/MacroTestingTests/DictionaryStorageMacroTests.swift
@@ -14,38 +14,73 @@ final class DictionaryStorageMacroTests: BaseTestCase {
   }
 
   func testExpansionConvertsStoredProperties() {
-    assertMacro {
-      """
-      @DictionaryStorage
-      struct Point {
-        var x: Int = 1
-        var y: Int = 2
-      }
-      """
-    } expansion: {
-      """
-      struct Point {
-        var x: Int = 1 {
-          get {
-            _storage["x", default: 1] as! Int
+    #if canImport(SwiftSyntax510)
+      assertMacro {
+        """
+        @DictionaryStorage
+        struct Point {
+          var x: Int = 1
+          var y: Int = 2
+        }
+        """
+      } expansion: {
+        """
+        struct Point {
+          var x: Int {
+            get {
+              _storage["x", default: 1] as! Int
+            }
+            set {
+              _storage["x"] = newValue
+            }
           }
-          set {
-            _storage["x"] = newValue
+          var y: Int {
+            get {
+              _storage["y", default: 2] as! Int
+            }
+            set {
+              _storage["y"] = newValue
+            }
           }
+
+          var _storage: [String: Any] = [:]
+        }
+        """
+      }
+    #elseif canImport(SwiftSyntax509)
+      assertMacro {
+        """
+        @DictionaryStorage
+        struct Point {
+          var x: Int = 1
+          var y: Int = 2
         }
-        var y: Int = 2 {
-          get {
-            _storage["y", default: 2] as! Int
+        """
+      } expansion: {
+        """
+        struct Point {
+          var x: Int = 1 {
+            get {
+              _storage["x", default: 1] as! Int
+            }
+            set {
+              _storage["x"] = newValue
+            }
           }
-          set {
-            _storage["y"] = newValue
+          var y: Int = 2 {
+            get {
+              _storage["y", default: 2] as! Int
+            }
+            set {
+              _storage["y"] = newValue
+            }
           }
-        }
 
-        var _storage: [String: Any] = [:]
+          var _storage: [String: Any] = [:]
+        }
+        """
       }
-      """
-    }
+    #endif
   }
 
   func testExpansionWithoutInitializersEmitsError() {
diff --git a/Tests/MacroTestingTests/MacroExamples/AddBlocker.swift b/Tests/MacroTestingTests/MacroExamples/AddBlocker.swift
index b0db043..58dfd7b 100644
--- a/Tests/MacroTestingTests/MacroExamples/AddBlocker.swift
+++ b/Tests/MacroTestingTests/MacroExamples/AddBlocker.swift
@@ -101,6 +101,6 @@ public struct AddBlocker: ExpressionMacro {
       context.diagnose(diag)
     }
 
-    return result.asProtocol(FreestandingMacroExpansionSyntax.self)!.argumentList.first!.expression
+    return result.asProtocol(FreestandingMacroExpansionSyntax.self)!.arguments.first!.expression
   }
 }
diff --git a/Tests/MacroTestingTests/MacroExamples/FontLiteralMacro.swift b/Tests/MacroTestingTests/MacroExamples/FontLiteralMacro.swift
index 97aedda..0559ace 100644
--- a/Tests/MacroTestingTests/MacroExamples/FontLiteralMacro.swift
+++ b/Tests/MacroTestingTests/MacroExamples/FontLiteralMacro.swift
@@ -22,7 +22,7 @@ public enum FontLiteralMacro: ExpressionMacro {
     in context: some MacroExpansionContext
   ) throws -> ExprSyntax {
     let argList = replaceFirstLabel(
-      of: node.argumentList,
+      of: node.arguments,
       with: "fontLiteralName"
     )
     return ".init(\(argList))"
diff --git a/Tests/MacroTestingTests/MacroExamples/StringifyMacro.swift b/Tests/MacroTestingTests/MacroExamples/StringifyMacro.swift
index e351b6b..5d0d7c8 100644
--- a/Tests/MacroTestingTests/MacroExamples/StringifyMacro.swift
+++ b/Tests/MacroTestingTests/MacroExamples/StringifyMacro.swift
@@ -28,7 +28,7 @@ public enum StringifyMacro: ExpressionMacro {
     of node: some FreestandingMacroExpansionSyntax,
     in context: some MacroExpansionContext
   ) -> ExprSyntax {
-    guard let argument = node.argumentList.first?.expression else {
+    guard let argument = node.arguments.first?.expression else {
       fatalError("compiler bug: the macro does not have any arguments")
     }
 
diff --git a/Tests/MacroTestingTests/MacroExamples/SwiftSyntaxCompatibilityExtensions.swift b/Tests/MacroTestingTests/MacroExamples/SwiftSyntaxCompatibilityExtensions.swift
new file mode 100644
index 0000000..909cba7
--- /dev/null
+++ b/Tests/MacroTestingTests/MacroExamples/SwiftSyntaxCompatibilityExtensions.swift
@@ -0,0 +1,11 @@
+import SwiftSyntax
+import SwiftSyntaxMacros
+
+#if !canImport(SwiftSyntax510) && canImport(SwiftSyntax509)
+  extension FreestandingMacroExpansionSyntax {
+    var arguments: LabeledExprListSyntax {
+      get { self.argumentList }
+      set { self.argumentList = newValue }
+    }
+  }
+#endif
diff --git a/Tests/MacroTestingTests/MacroExamples/URLMacro.swift b/Tests/MacroTestingTests/MacroExamples/URLMacro.swift
index 44054a2..5b5ccf8 100644
--- a/Tests/MacroTestingTests/MacroExamples/URLMacro.swift
+++ b/Tests/MacroTestingTests/MacroExamples/URLMacro.swift
@@ -21,7 +21,7 @@ public enum URLMacro: ExpressionMacro {
     of node: some FreestandingMacroExpansionSyntax,
     in context: some MacroExpansionContext
   ) throws -> ExprSyntax {
-    guard let argument = node.argumentList.first?.expression,
+    guard let argument = node.arguments.first?.expression,
       let segments = argument.as(StringLiteralExprSyntax.self)?.segments,
       segments.count == 1,
       case .stringSegment(let literalSegment)? = segments.first
diff --git a/Tests/MacroTestingTests/MacroExamples/WarningMacro.swift b/Tests/MacroTestingTests/MacroExamples/WarningMacro.swift
index 35a0c9d..9f2163c 100644
--- a/Tests/MacroTestingTests/MacroExamples/WarningMacro.swift
+++ b/Tests/MacroTestingTests/MacroExamples/WarningMacro.swift
@@ -21,7 +21,7 @@ public enum WarningMacro: ExpressionMacro {
     of node: some FreestandingMacroExpansionSyntax,
     in context: some MacroExpansionContext
   ) throws -> ExprSyntax {
-    guard let firstElement = node.argumentList.first,
+    guard let firstElement = node.arguments.first,
       let stringLiteral = firstElement.expression
         .as(StringLiteralExprSyntax.self),
       stringLiteral.segments.count == 1,
diff --git a/Tests/MemberwiseInitTests/MemberwiseInitTests.swift b/Tests/MemberwiseInitTests/MemberwiseInitTests.swift
index 89ff084..e86ae6d 100644
--- a/Tests/MemberwiseInitTests/MemberwiseInitTests.swift
+++ b/Tests/MemberwiseInitTests/MemberwiseInitTests.swift
@@ -2046,84 +2046,188 @@ final class MemberwiseInitTests: XCTestCase {
     }
   }
 
+  // TODO: regress MemberwiseInit to match swift-syntax 5.10 limitation
   func testCustomInitEscapingWithMultipleBindings() {
-    assertMacro {
-      """
-      @MemberwiseInit
-      struct S {
-        @Init(escaping: true)
-        let v, r: T
+    #if canImport(SwiftSyntax510)
+      assertMacro {
+        """
+        @MemberwiseInit
+        struct S {
+          @Init(escaping: true)
+          let v, r: T
+        }
+        """
+      } expansion: {
+        """
+        struct S {
+          let v, r: T
+
+          internal init(
+            v: @escaping T,
+            r: @escaping T
+          ) {
+            self.v = v
+            self.r = r
+          }
+        }
+        """
+      } diagnostics: {
+        """
+        @MemberwiseInit
+        struct S {
+          @Init(escaping: true)
+          ┬────────────────────
+          ╰─ 🛑 peer macro can only be applied to a single variable
+          let v, r: T
+        }
+        """
       }
-      """
-    } expansion: {
-      """
-      struct S {
-        let v, r: T
+    #elseif canImport(SwfitSyntax509)
+      assertMacro {
+        """
+        @MemberwiseInit
+        struct S {
+          @Init(escaping: true)
+          let v, r: T
+        }
+        """
+      } expansion: {
+        """
+        struct S {
+          let v, r: T
 
-        internal init(
-          v: @escaping T,
-          r: @escaping T
-        ) {
-          self.v = v
-          self.r = r
+          internal init(
+            v: @escaping T,
+            r: @escaping T
+          ) {
+            self.v = v
+            self.r = r
+          }
         }
+        """
       }
-      """
-    }
+    #endif
   }
 
+  // TODO: Consider regressing MemberwiseInit to match swift-syntax 5.10 limitation (or leave redundant error, but that has a fix-it)
   func testCustomLabelWithMultipleBindings_FailsWithDiagnostic() {
-    assertMacro {
-      """
-      @MemberwiseInit(.public)
-      public struct Person {
-        @Init(label: "with") public let firstName, lastName: String
-      }
-      """
-    } expansion: {
-      """
-      public struct Person {
-        public let firstName, lastName: String
-
-        public init() {
+    #if canImport(SwiftSyntax510)
+      assertMacro {
+        """
+        @MemberwiseInit(.public)
+        public struct Person {
+          @Init(label: "with") public let firstName, lastName: String
+        }
+        """
+      } expansion: {
+        """
+        public struct Person {
+          public let firstName, lastName: String
+
+          public init() {
+          }
         }
+        """
+      } diagnostics: {
+        """
+        @MemberwiseInit(.public)
+        public struct Person {
+          @Init(label: "with") public let firstName, lastName: String
+                ┬────────────
+          │     ╰─ 🛑 Custom 'label' can't be applied to multiple bindings
+          ┬───────────────────
+          ╰─ 🛑 peer macro can only be applied to a single variable
+        }
+        """
+      }
+    #elseif canImport(SwfitSyntax509)
+      assertMacro {
+        """
+        @MemberwiseInit(.public)
+        public struct Person {
+          @Init(label: "with") public let firstName, lastName: String
+        }
+        """
+      } expansion: {
+        """
+        public struct Person {
+          public let firstName, lastName: String
+
+          public init() {
+          }
+        }
+        """
+      } diagnostics: {
+        """
+        @MemberwiseInit(.public)
+        public struct Person {
+          @Init(label: "with") public let firstName, lastName: String
+                ┬────────────
+                ╰─ 🛑 Custom 'label' can't be applied to multiple bindings
+        }
+        """
       }
-      """
-    } diagnostics: {
-      """
-      @MemberwiseInit(.public)
-      public struct Person {
-        @Init(label: "with") public let firstName, lastName: String
-              ┬────────────
-              ╰─ 🛑 Custom 'label' can't be applied to multiple bindings
-      }
-      """
-    }
+    #endif
   }
 
+  // TODO: Consider regressing MemberwiseInit to match swift-syntax 5.10 limitation (or leave redundant error, but that has a fix-it)
   func testLabellessCustomInitForMultipleBindings() {
-    assertMacro {
-      """
-      @MemberwiseInit(.public)
-      public struct Person {
-        @Init(label: "_") public let firstName, lastName: String
-      }
-      """
-    } expansion: {
-      """
-      public struct Person {
-        public let firstName, lastName: String
-
-        public init(
-          _ firstName: String,
-          _ lastName: String
-        ) {
-          self.firstName = firstName
-          self.lastName = lastName
+    #if canImport(SwiftSyntax510)
+      assertMacro {
+        """
+        @MemberwiseInit(.public)
+        public struct Person {
+          @Init(label: "_") public let firstName, lastName: String
+        }
+        """
+      } expansion: {
+        """
+        public struct Person {
+          public let firstName, lastName: String
+
+          public init(
+            _ firstName: String,
+            _ lastName: String
+          ) {
+            self.firstName = firstName
+            self.lastName = lastName
+          }
+        }
+        """
+      } diagnostics: {
+        """
+        @MemberwiseInit(.public)
+        public struct Person {
+          @Init(label: "_") public let firstName, lastName: String
+          ┬────────────────
+          ╰─ 🛑 peer macro can only be applied to a single variable
+        }
+        """
+      }
+    #elseif canImport(SwfitSyntax509)
+      assertMacro {
+        """
+        @MemberwiseInit(.public)
+        public struct Person {
+          @Init(label: "_") public let firstName, lastName: String
+        }
+        """
+      } expansion: {
+        """
+        public struct Person {
+          public let firstName, lastName: String
+
+          public init(
+            _ firstName: String,
+            _ lastName: String
+          ) {
+            self.firstName = firstName
+            self.lastName = lastName
+          }
         }
+        """
       }
-      """
-    }
+    #endif
   }
 
   func testCustomInitIgnore() {