diff --git a/.travis.yml b/.travis.yml
index ebd8151..4997cc4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,10 +1,10 @@
 language: objective-c
-osx_image: xcode9
+osx_image: xcode10.2
 
 env:
-  - ACTION=test  PLATFORM=Mac     DESTINATION='platform=OS X'
+  - ACTION=test  PLATFORM=Mac     DESTINATION='platform=macOS'
   - ACTION=test  PLATFORM=iOS     DESTINATION='platform=iOS Simulator,name=iPhone 6S'
-  - ACTION=test  PLATFORM=tvOS    DESTINATION='platform=tvOS Simulator,name=Apple TV 1080p'
+  - ACTION=test  PLATFORM=tvOS    DESTINATION='platform=tvOS Simulator,name=Apple TV 4K (at 1080p)'
 
 script:
   - set -o pipefail && xcodebuild -scheme SnapKit -destination "$DESTINATION" $ACTION | xcpretty
diff --git a/SnapKit.podspec b/SnapKit.podspec
index b55866a..d7d093d 100644
--- a/SnapKit.podspec
+++ b/SnapKit.podspec
@@ -14,5 +14,5 @@ Pod::Spec.new do |s|
 
   s.source_files = 'Source/*.swift'
 
-  s.swift_version = '4.2'
+  s.swift_version = '5.0'
 end
diff --git a/SnapKit.xcodeproj/project.pbxproj b/SnapKit.xcodeproj/project.pbxproj
index 0bd8d9e..53ab8b9 100644
--- a/SnapKit.xcodeproj/project.pbxproj
+++ b/SnapKit.xcodeproj/project.pbxproj
@@ -310,11 +310,11 @@
 				TargetAttributes = {
 					EEBCC9D719CC627D0083B827 = {
 						CreatedOnToolsVersion = 6.0;
-						LastSwiftMigration = 0900;
+						LastSwiftMigration = 1020;
 					};
 					EEBCC9E119CC627D0083B827 = {
 						CreatedOnToolsVersion = 6.0;
-						LastSwiftMigration = 0900;
+						LastSwiftMigration = 1020;
 						ProvisioningStyle = Automatic;
 					};
 				};
@@ -533,7 +533,7 @@
 				SKIP_INSTALL = YES;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				VERSIONING_SYSTEM = "apple-generic";
 			};
 			name = Debug;
@@ -553,7 +553,7 @@
 				PRODUCT_NAME = SnapKit;
 				SKIP_INSTALL = YES;
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				VERSIONING_SYSTEM = "apple-generic";
 			};
 			name = Release;
@@ -567,7 +567,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks @loader_path/../Frameworks @executable_path/../Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = "io.snapkit.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 4.2;
 			};
 			name = Debug;
 		};
@@ -581,7 +581,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "io.snapkit.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 4.2;
 			};
 			name = Release;
 		};
diff --git a/Source/Constraint.swift b/Source/Constraint.swift
index 6e4948e..dc2c7c8 100644
--- a/Source/Constraint.swift
+++ b/Source/Constraint.swift
@@ -189,12 +189,12 @@ public final class Constraint {
 
     // MARK: Public
 
-    @available(*, deprecated:3.0, message:"Use activate().")
+    @available(*, deprecated, message:"Use activate().")
     public func install() {
         self.activate()
     }
 
-    @available(*, deprecated:3.0, message:"Use deactivate().")
+    @available(*, deprecated, message:"Use deactivate().")
     public func uninstall() {
         self.deactivate()
     }
@@ -231,25 +231,25 @@ public final class Constraint {
         return self
     }
 
-    @available(*, deprecated:3.0, message:"Use update(offset: ConstraintOffsetTarget) instead.")
+    @available(*, deprecated, message:"Use update(offset: ConstraintOffsetTarget) instead.")
     public func updateOffset(amount: ConstraintOffsetTarget) -> Void { self.update(offset: amount) }
 
-    @available(*, deprecated:3.0, message:"Use update(inset: ConstraintInsetTarget) instead.")
+    @available(*, deprecated, message:"Use update(inset: ConstraintInsetTarget) instead.")
     public func updateInsets(amount: ConstraintInsetTarget) -> Void { self.update(inset: amount) }
 
-    @available(*, deprecated:3.0, message:"Use update(priority: ConstraintPriorityTarget) instead.")
+    @available(*, deprecated, message:"Use update(priority: ConstraintPriorityTarget) instead.")
     public func updatePriority(amount: ConstraintPriorityTarget) -> Void { self.update(priority: amount) }
 
-    @available(*, obsoleted:3.0, message:"Use update(priority: ConstraintPriorityTarget) instead.")
+    @available(*, deprecated, message:"Use update(priority: ConstraintPriorityTarget) instead.")
     public func updatePriorityRequired() -> Void {}
 
-    @available(*, obsoleted:3.0, message:"Use update(priority: ConstraintPriorityTarget) instead.")
+    @available(*, deprecated, message:"Use update(priority: ConstraintPriorityTarget) instead.")
     public func updatePriorityHigh() -> Void { fatalError("Must be implemented by Concrete subclass.") }
 
-    @available(*, obsoleted:3.0, message:"Use update(priority: ConstraintPriorityTarget) instead.")
+    @available(*, deprecated, message:"Use update(priority: ConstraintPriorityTarget) instead.")
     public func updatePriorityMedium() -> Void { fatalError("Must be implemented by Concrete subclass.") }
 
-    @available(*, obsoleted:3.0, message:"Use update(priority: ConstraintPriorityTarget) instead.")
+    @available(*, deprecated, message:"Use update(priority: ConstraintPriorityTarget) instead.")
     public func updatePriorityLow() -> Void { fatalError("Must be implemented by Concrete subclass.") }
 
     // MARK: Internal
diff --git a/Source/ConstraintConstantTarget.swift b/Source/ConstraintConstantTarget.swift
index bc6d596..7224df9 100644
--- a/Source/ConstraintConstantTarget.swift
+++ b/Source/ConstraintConstantTarget.swift
@@ -82,7 +82,11 @@ extension ConstraintConstantTarget {
                     return value.y
                 case .width, .height, .notAnAttribute:
                     return 0.0
-                }
+                #if swift(>=5.0)
+                @unknown default:
+                    return 0.0
+                #endif
+            }
             #else
                 switch layoutAttribute {
                 case .left, .right, .leading, .trailing, .centerX:
@@ -91,7 +95,11 @@ extension ConstraintConstantTarget {
                     return value.y
                 case .width, .height, .notAnAttribute:
                     return 0.0
-                }
+                #if swift(>=5.0)
+                @unknown default:
+                    return 0.0
+                #endif
+            }
             #endif
         }
         
@@ -116,7 +124,11 @@ extension ConstraintConstantTarget {
                     return -(value.top + value.bottom)
                 case .notAnAttribute:
                     return 0.0
-                }
+                #if swift(>=5.0)
+                @unknown default:
+                    return 0.0
+                #endif
+            }
             #else
                 switch layoutAttribute {
                 case .left, .centerX:
@@ -137,7 +149,11 @@ extension ConstraintConstantTarget {
                     return -(value.top + value.bottom)
                 case .notAnAttribute:
                     return 0.0
-                }
+                #if swift(>=5.0)
+                @unknown default:
+                    return 0.0
+                #endif
+            }
             #endif
         }
         
diff --git a/Source/ConstraintDSL.swift b/Source/ConstraintDSL.swift
index a7e1798..b7aad57 100644
--- a/Source/ConstraintDSL.swift
+++ b/Source/ConstraintDSL.swift
@@ -115,7 +115,7 @@ extension ConstraintAttributesDSL {
     
     // MARK: Baselines
     
-    @available(*, deprecated:3.0, message:"Use .lastBaseline instead")
+    @available(*, deprecated, message:"Use .lastBaseline instead")
     public var baseline: ConstraintItem {
         return ConstraintItem(target: self.target, attributes: ConstraintAttributes.lastBaseline)
     }
diff --git a/Source/ConstraintLayoutGuide+Extensions.swift b/Source/ConstraintLayoutGuide+Extensions.swift
index c2d9e9d..d429e0c 100644
--- a/Source/ConstraintLayoutGuide+Extensions.swift
+++ b/Source/ConstraintLayoutGuide+Extensions.swift
@@ -29,7 +29,7 @@
 @available(iOS 9.0, OSX 10.11, *)
 public extension ConstraintLayoutGuide {
     
-    public var snp: ConstraintLayoutGuideDSL {
+    var snp: ConstraintLayoutGuideDSL {
         return ConstraintLayoutGuideDSL(guide: self)
     }
     
diff --git a/Source/ConstraintMaker.swift b/Source/ConstraintMaker.swift
index 91f35f1..ed2879b 100644
--- a/Source/ConstraintMaker.swift
+++ b/Source/ConstraintMaker.swift
@@ -69,7 +69,7 @@ public class ConstraintMaker {
         return self.makeExtendableWithAttributes(.centerY)
     }
     
-    @available(*, deprecated:3.0, message:"Use lastBaseline instead")
+    @available(*, deprecated, message:"Use lastBaseline instead")
     public var baseline: ConstraintMakerExtendable {
         return self.makeExtendableWithAttributes(.lastBaseline)
     }
diff --git a/Source/ConstraintMakerExtendable.swift b/Source/ConstraintMakerExtendable.swift
index 6a755b5..243e54e 100644
--- a/Source/ConstraintMakerExtendable.swift
+++ b/Source/ConstraintMakerExtendable.swift
@@ -80,7 +80,7 @@ public class ConstraintMakerExtendable: ConstraintMakerRelatable {
         return self
     }
     
-    @available(*, deprecated:3.0, message:"Use lastBaseline instead")
+    @available(*, deprecated, message:"Use lastBaseline instead")
     public var baseline: ConstraintMakerExtendable {
         self.description.attributes += .lastBaseline
         return self
diff --git a/Source/ConstraintMakerPriortizable.swift b/Source/ConstraintMakerPriortizable.swift
index ef79448..e0d452d 100644
--- a/Source/ConstraintMakerPriortizable.swift
+++ b/Source/ConstraintMakerPriortizable.swift
@@ -42,25 +42,25 @@ public class ConstraintMakerPriortizable: ConstraintMakerFinalizable {
         return self
     }
     
-    @available(*, deprecated:3.0, message:"Use priority(.required) instead.")
+    @available(*, deprecated, message:"Use priority(.required) instead.")
     @discardableResult
     public func priorityRequired() -> ConstraintMakerFinalizable {
         return self.priority(.required)
     }
     
-    @available(*, deprecated:3.0, message:"Use priority(.high) instead.")
+    @available(*, deprecated, message:"Use priority(.high) instead.")
     @discardableResult
     public func priorityHigh() -> ConstraintMakerFinalizable {
         return self.priority(.high)
     }
     
-    @available(*, deprecated:3.0, message:"Use priority(.medium) instead.")
+    @available(*, deprecated, message:"Use priority(.medium) instead.")
     @discardableResult
     public func priorityMedium() -> ConstraintMakerFinalizable {
         return self.priority(.medium)
     }
     
-    @available(*, deprecated:3.0, message:"Use priority(.low) instead.")
+    @available(*, deprecated, message:"Use priority(.low) instead.")
     @discardableResult
     public func priorityLow() -> ConstraintMakerFinalizable {
         return self.priority(.low)
diff --git a/Source/ConstraintView+Extensions.swift b/Source/ConstraintView+Extensions.swift
index 77afad9..a4898dc 100644
--- a/Source/ConstraintView+Extensions.swift
+++ b/Source/ConstraintView+Extensions.swift
@@ -30,122 +30,122 @@
 
 public extension ConstraintView {
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_left: ConstraintItem { return self.snp.left }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_left: ConstraintItem { return self.snp.left }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_top: ConstraintItem { return self.snp.top }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_top: ConstraintItem { return self.snp.top }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_right: ConstraintItem { return self.snp.right }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_right: ConstraintItem { return self.snp.right }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_bottom: ConstraintItem { return self.snp.bottom }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_bottom: ConstraintItem { return self.snp.bottom }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_leading: ConstraintItem { return self.snp.leading }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_leading: ConstraintItem { return self.snp.leading }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_trailing: ConstraintItem { return self.snp.trailing }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_trailing: ConstraintItem { return self.snp.trailing }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_width: ConstraintItem { return self.snp.width }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_width: ConstraintItem { return self.snp.width }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_height: ConstraintItem { return self.snp.height }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_height: ConstraintItem { return self.snp.height }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_centerX: ConstraintItem { return self.snp.centerX }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_centerX: ConstraintItem { return self.snp.centerX }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_centerY: ConstraintItem { return self.snp.centerY }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_centerY: ConstraintItem { return self.snp.centerY }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_baseline: ConstraintItem { return self.snp.baseline }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_baseline: ConstraintItem { return self.snp.baseline }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, OSX 10.11, *)
-    public var snp_lastBaseline: ConstraintItem { return self.snp.lastBaseline }
+    var snp_lastBaseline: ConstraintItem { return self.snp.lastBaseline }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, OSX 10.11, *)
-    public var snp_firstBaseline: ConstraintItem { return self.snp.firstBaseline }
+    var snp_firstBaseline: ConstraintItem { return self.snp.firstBaseline }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, *)
-    public var snp_leftMargin: ConstraintItem { return self.snp.leftMargin }
+    var snp_leftMargin: ConstraintItem { return self.snp.leftMargin }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, *)
-    public var snp_topMargin: ConstraintItem { return self.snp.topMargin }
+    var snp_topMargin: ConstraintItem { return self.snp.topMargin }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, *)
-    public var snp_rightMargin: ConstraintItem { return self.snp.rightMargin }
+    var snp_rightMargin: ConstraintItem { return self.snp.rightMargin }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, *)
-    public var snp_bottomMargin: ConstraintItem { return self.snp.bottomMargin }
+    var snp_bottomMargin: ConstraintItem { return self.snp.bottomMargin }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, *)
-    public var snp_leadingMargin: ConstraintItem { return self.snp.leadingMargin }
+    var snp_leadingMargin: ConstraintItem { return self.snp.leadingMargin }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, *)
-    public var snp_trailingMargin: ConstraintItem { return self.snp.trailingMargin }
+    var snp_trailingMargin: ConstraintItem { return self.snp.trailingMargin }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, *)
-    public var snp_centerXWithinMargins: ConstraintItem { return self.snp.centerXWithinMargins }
+    var snp_centerXWithinMargins: ConstraintItem { return self.snp.centerXWithinMargins }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, *)
-    public var snp_centerYWithinMargins: ConstraintItem { return self.snp.centerYWithinMargins }
+    var snp_centerYWithinMargins: ConstraintItem { return self.snp.centerYWithinMargins }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_edges: ConstraintItem { return self.snp.edges }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_edges: ConstraintItem { return self.snp.edges }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_size: ConstraintItem { return self.snp.size }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_size: ConstraintItem { return self.snp.size }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public var snp_center: ConstraintItem { return self.snp.center }
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    var snp_center: ConstraintItem { return self.snp.center }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, *)
-    public var snp_margins: ConstraintItem { return self.snp.margins }
+    var snp_margins: ConstraintItem { return self.snp.margins }
     
-    @available(iOS, deprecated:3.0, message:"Use newer snp.* syntax.")
+    @available(iOS, deprecated, message:"Use newer snp.* syntax.")
     @available(iOS 8.0, *)
-    public var snp_centerWithinMargins: ConstraintItem { return self.snp.centerWithinMargins }
+    var snp_centerWithinMargins: ConstraintItem { return self.snp.centerWithinMargins }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public func snp_prepareConstraints(_ closure: (_ make: ConstraintMaker) -> Void) -> [Constraint] {
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    func snp_prepareConstraints(_ closure: (_ make: ConstraintMaker) -> Void) -> [Constraint] {
         return self.snp.prepareConstraints(closure)
     }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public func snp_makeConstraints(_ closure: (_ make: ConstraintMaker) -> Void) {
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    func snp_makeConstraints(_ closure: (_ make: ConstraintMaker) -> Void) {
         self.snp.makeConstraints(closure)
     }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public func snp_remakeConstraints(_ closure: (_ make: ConstraintMaker) -> Void) {
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    func snp_remakeConstraints(_ closure: (_ make: ConstraintMaker) -> Void) {
         self.snp.remakeConstraints(closure)
     }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public func snp_updateConstraints(_ closure: (_ make: ConstraintMaker) -> Void) {
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    func snp_updateConstraints(_ closure: (_ make: ConstraintMaker) -> Void) {
         self.snp.updateConstraints(closure)
     }
     
-    @available(*, deprecated:3.0, message:"Use newer snp.* syntax.")
-    public func snp_removeConstraints() {
+    @available(*, deprecated, message:"Use newer snp.* syntax.")
+    func snp_removeConstraints() {
         self.snp.removeConstraints()
     }
     
-    public var snp: ConstraintViewDSL {
+    var snp: ConstraintViewDSL {
         return ConstraintViewDSL(view: self)
     }
     
diff --git a/Source/Debugging.swift b/Source/Debugging.swift
index 55f5b87..a78579a 100644
--- a/Source/Debugging.swift
+++ b/Source/Debugging.swift
@@ -29,7 +29,7 @@
 
 public extension LayoutConstraint {
     
-    override public var description: String {
+    override var description: String {
         var description = "<"
         
         description += descriptionForObject(self)
@@ -82,6 +82,9 @@ private func descriptionForRelation(_ relation: LayoutRelation) -> String {
     case .equal:                return "=="
     case .greaterThanOrEqual:   return ">="
     case .lessThanOrEqual:      return "<="
+    #if swift(>=5.0)
+    @unknown default:           return "unknown"
+    #endif
     }
 }
 
@@ -109,7 +112,10 @@ private func descriptionForAttribute(_ attribute: LayoutAttribute) -> String {
         case .trailingMargin:       return "trailingMargin"
         case .centerXWithinMargins: return "centerXWithinMargins"
         case .centerYWithinMargins: return "centerYWithinMargins"
-        }
+        #if swift(>=5.0)
+        @unknown default:           return "unknown"
+        #endif
+    }
     #else
         switch attribute {
         case .notAnAttribute:       return "notAnAttribute"
@@ -125,7 +131,10 @@ private func descriptionForAttribute(_ attribute: LayoutAttribute) -> String {
         case .centerY:              return "centerY"
         case .lastBaseline:         return "lastBaseline"
         case .firstBaseline:        return "firstBaseline"
-        }
+        #if swift(>=5.0)
+        @unknown default:           return "unknown"
+        #endif
+    }
     #endif
 }
 
diff --git a/Source/UILayoutSupport+Extensions.swift b/Source/UILayoutSupport+Extensions.swift
index cfbce2e..8e7644c 100644
--- a/Source/UILayoutSupport+Extensions.swift
+++ b/Source/UILayoutSupport+Extensions.swift
@@ -29,7 +29,7 @@
 @available(iOS 8.0, *)
 public extension ConstraintLayoutSupport {
     
-    public var snp: ConstraintLayoutSupportDSL {
+    var snp: ConstraintLayoutSupportDSL {
         return ConstraintLayoutSupportDSL(support: self)
     }
     
diff --git a/Tests/SnapKitTests/Tests.swift b/Tests/SnapKitTests/Tests.swift
index dd4a309..a4b587f 100644
--- a/Tests/SnapKitTests/Tests.swift
+++ b/Tests/SnapKitTests/Tests.swift
@@ -494,8 +494,8 @@ class SnapKitTests: XCTestCase {
     
     #if os(iOS) || os(tvOS)
     func testEdgesToMargins() {
-        var fromAttributes = Set<NSLayoutAttribute>()
-        var toAttributes = Set<NSLayoutAttribute>()
+        var fromAttributes = Set<LayoutAttribute>()
+        var toAttributes = Set<LayoutAttribute>()
         
         let view = View()
         self.container.addSubview(view)