If OkHttp is present, require 1.6.0 or better.

pom.xml

@@ -50,7 +50,7 @@
     <android.version>4.1.1.4</android.version>
     <android.platform>16</android.platform>
     <gson.version>2.2.4</gson.version>
-    <okhttp.version>1.3.0</okhttp.version>
+    <okhttp.version>1.6.0</okhttp.version>
     <rxjava.version>0.18.3</rxjava.version>
     <appengine.version>1.8.9</appengine.version>
 
@@ -103,6 +103,11 @@
         <artifactId>okhttp</artifactId>
         <version>${okhttp.version}</version>
       </dependency>
+      <dependency>
+        <groupId>com.squareup.okhttp</groupId>
+        <artifactId>okhttp-urlconnection</artifactId>
+        <version>${okhttp.version}</version>
+      </dependency>
       <dependency>
         <groupId>com.google.code.gson</groupId>
         <artifactId>gson</artifactId>

retrofit/pom.xml

@@ -29,6 +29,11 @@
       <artifactId>okhttp</artifactId>
       <optional>true</optional>
     </dependency>
+    <dependency>
+      <groupId>com.squareup.okhttp</groupId>
+      <artifactId>okhttp-urlconnection</artifactId>
+      <optional>true</optional>
+    </dependency>
     <dependency>
       <groupId>com.netflix.rxjava</groupId>
       <artifactId>rxjava-core</artifactId>

retrofit/src/main/java/retrofit/Platform.java

@@ -166,14 +166,32 @@ private static class AppEngine extends Base {
     }
   }
 
-  /** Determine whether or not OkHttp is present on the runtime classpath. */
+  /** Determine whether or not OkHttp 1.6 or newer is present on the runtime classpath. */
   private static boolean hasOkHttpOnClasspath() {
+    boolean okUrlFactory = false;
+    try {
+      Class.forName("com.squareup.okhttp.OkUrlFactory");
+      okUrlFactory = true;
+    } catch (ClassNotFoundException e) {
+    }
+
+    boolean okHttpClient = false;
     try {
       Class.forName("com.squareup.okhttp.OkHttpClient");
-      return true;
+      okHttpClient = true;
     } catch (ClassNotFoundException e) {
-      return false;
     }
+
+    if (okHttpClient != okUrlFactory) {
+      throw new RuntimeException(""
+          + "Retrofit detected an unsupported OkHttp on the classpath.\n"
+          + "To use OkHttp with this version of Retrofit, you'll need:\n"
+          + "1. com.squareup.okhttp:okhttp:1.6.0 (or newer)\n"
+          + "2. com.squareup.okhttp:okhttp-urlconnection:1.6.0 (or newer)\n"
+          + "Note that OkHttp 2.0.0+ is supported!");
+    }
+
+    return okHttpClient;
   }
 
   /**

retrofit/src/main/java/retrofit/client/OkClient.java

@@ -16,6 +16,7 @@
 package retrofit.client;
 
 import com.squareup.okhttp.OkHttpClient;
+import com.squareup.okhttp.OkUrlFactory;
 import java.io.IOException;
 import java.net.HttpURLConnection;
 import java.net.URL;
@@ -30,17 +31,17 @@ private static OkHttpClient generateDefaultOkHttp() {
     return client;
   }
 
-  private final OkHttpClient client;
+  private final OkUrlFactory okUrlFactory;
 
   public OkClient() {
     this(generateDefaultOkHttp());
   }
 
   public OkClient(OkHttpClient client) {
-    this.client = client;
+    this.okUrlFactory = new OkUrlFactory(client);
   }
 
   @Override protected HttpURLConnection openConnection(Request request) throws IOException {
-    return client.open(new URL(request.getUrl()));
+    return okUrlFactory.open(new URL(request.getUrl()));
   }
 }