diff --git a/andlinker/src/main/java/com/codezjx/andlinker/adapter/DefaultCallAdapterFactory.java b/andlinker/src/main/java/com/codezjx/andlinker/adapter/DefaultCallAdapterFactory.java
index cf18138..8e21b57 100644
--- a/andlinker/src/main/java/com/codezjx/andlinker/adapter/DefaultCallAdapterFactory.java
+++ b/andlinker/src/main/java/com/codezjx/andlinker/adapter/DefaultCallAdapterFactory.java
@@ -14,14 +14,36 @@ public class DefaultCallAdapterFactory extends CallAdapter.Factory {
     public static final CallAdapter.Factory INSTANCE = new DefaultCallAdapterFactory();
 
     @Override
-    public CallAdapter<?, ?> get(Type returnType, Annotation[] annotations) {
+    public CallAdapter<?, ?> get(final Type returnType, Annotation[] annotations) {
         return new CallAdapter<Object, Object>() {
             @Override
             public Object adapt(Call<Object> call) {
+                Class<?> rawType = getRawType(returnType);
+                Object result = call.execute();
+                if (result == null) {
+                    result = createDefaultResult(rawType);
+                }
                 // Return the result
-                return call.execute();
+                return result;
             }
         };
     }
+
+    private Object createDefaultResult(Class<?> returnType) {
+        // For java.lang.NullPointerException: Expected to unbox a 'xxx' primitive type but was returned null
+        // Visit https://github.com/codezjx/AndLinker/issues/14
+        if (returnType == byte.class) {
+            return (byte) 0;
+        } else if (returnType == short.class) {
+            return (short) 0;
+        } else if (returnType == int.class || returnType == long.class || returnType == float.class || returnType == double.class) {
+            return 0;
+        } else if (returnType == boolean.class) {
+            return false;
+        } else if (returnType == char.class) {
+            return ' ';
+        }
+        return null;
+    }
     
 }