diff --git a/Sources/SwiftyImage/SwiftyImage.swift b/Sources/SwiftyImage/SwiftyImage.swift
index ca9e32f..1e87969 100644
--- a/Sources/SwiftyImage/SwiftyImage.swift
+++ b/Sources/SwiftyImage/SwiftyImage.swift
@@ -28,7 +28,9 @@ public extension UIImage {
 
   class func with(size: CGSize, opaque: Bool = false, scale: CGFloat = 0, block: ContextBlock) -> UIImage {
     UIGraphicsBeginImageContextWithOptions(size, opaque, scale)
-    let context = UIGraphicsGetCurrentContext()!
+    guard let context = UIGraphicsGetCurrentContext() else {
+        return UIImage()
+    }
     block(context)
     let image = UIGraphicsGetImageFromCurrentImageContext()
     UIGraphicsEndImageContext()
@@ -129,12 +131,12 @@ open class ImageDrawer {
       hasher.combine(UITraitCollection.current.userInterfaceStyle)
     }
 
-    hasher.combine(self.colors)
+    hasher.combine(self.colors.map({ $0.hexString() }))
     hasher.combine(self.colorLocations)
     hasher.combine(String(describing: self.colorStartPoint))
     hasher.combine(String(describing: self.colorEndPoint))
 
-    hasher.combine(self.borderColors)
+    hasher.combine(self.borderColors.map({ $0.hexString() }))
     hasher.combine(self.borderColorLocations)
     hasher.combine(String(describing: self.borderColorStartPoint))
     hasher.combine(String(describing: self.borderColorEndPoint))
@@ -472,4 +474,37 @@ public extension UIImage {
   }
 
 }
+
+extension UIColor {
+    fileprivate func hexString() -> String {
+        var red: CGFloat = 0
+        var green: CGFloat = 0
+        var blue: CGFloat = 0
+        var alpha: CGFloat = 0
+
+        let multiplier = CGFloat(255.999999)
+
+        guard self.getRed(&red, green: &green, blue: &blue, alpha: &alpha) else {
+            return ""
+        }
+
+        if alpha == 1.0 {
+            return String(
+                format: "#%02lX%02lX%02lX",
+                Int(red * multiplier),
+                Int(green * multiplier),
+                Int(blue * multiplier)
+            )
+        } else {
+            return String(
+                format: "#%02lX%02lX%02lX%02lX",
+                Int(red * multiplier),
+                Int(green * multiplier),
+                Int(blue * multiplier),
+                Int(alpha * multiplier)
+            )
+        }
+     }
+}
+
 #endif