diff --git a/Sources/Gzip/Data+Gzip.swift b/Sources/Gzip/Data+Gzip.swift
index c9f16bb..92ee408 100644
--- a/Sources/Gzip/Data+Gzip.swift
+++ b/Sources/Gzip/Data+Gzip.swift
@@ -114,29 +114,35 @@ public struct GzipError: Swift.Error {
     internal init(code: Int32, msg: UnsafePointer<CChar>?) {
         
         self.message = msg.flatMap { String(validatingUTF8: $0) } ?? "Unknown gzip error"
+        self.kind = Kind(code: code)
+    }
+    
+    
+    public var localizedDescription: String {
+        
+        return self.message
+    }
+}
+
+
+private extension GzipError.Kind {
+    
+    init(code: Int32) {
         
-        self.kind = {
-            switch code {
+        switch code {
             case Z_STREAM_ERROR:
-                return .stream
+                self = .stream
             case Z_DATA_ERROR:
-                return .data
+                self = .data
             case Z_MEM_ERROR:
-                return .memory
+                self = .memory
             case Z_BUF_ERROR:
-                return .buffer
+                self = .buffer
             case Z_VERSION_ERROR:
-                return .version
+                self = .version
             default:
-                return .unknown(code: Int(code))
-            }
-        }()
-    }
-    
-    
-    public var localizedDescription: String {
-        
-        return self.message
+                self = .unknown(code: Int(code))
+        }
     }
 }
 
@@ -285,7 +291,6 @@ extension Data {
                     
                     stream.next_in = nil
                 }
-                
             } while (status == Z_OK)
             
             totalIn += stream.total_in