diff --git a/build.gradle b/build.gradle
index 015e79c..59fe4fe 100644
--- a/build.gradle
+++ b/build.gradle
@@ -24,7 +24,6 @@ android {
 
     defaultConfig {
         minSdkVersion 15
-        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
         consumerProguardFiles 'proguard-rules.pro'
     }
 }
@@ -32,7 +31,6 @@ android {
 dependencies {
     api 'com.squareup.okhttp3:okhttp:4.1.1'
 
-    implementation 'com.android.support:support-annotations:28.0.0'
     implementation ('org.simpleframework:simple-xml:2.7.1') {
         exclude module: 'stax'
         exclude module: 'stax-api'
diff --git a/src/main/java/com/thegrizzlylabs/sardineandroid/impl/BasicAuthenticator.java b/src/main/java/com/thegrizzlylabs/sardineandroid/impl/BasicAuthenticator.java
index 0c39876..4d7661e 100644
--- a/src/main/java/com/thegrizzlylabs/sardineandroid/impl/BasicAuthenticator.java
+++ b/src/main/java/com/thegrizzlylabs/sardineandroid/impl/BasicAuthenticator.java
@@ -1,9 +1,5 @@
 package com.thegrizzlylabs.sardineandroid.impl;
 
-import android.support.annotation.NonNull;
-
-import java.io.IOException;
-
 import okhttp3.Authenticator;
 import okhttp3.Credentials;
 import okhttp3.Request;
@@ -18,13 +14,13 @@ class BasicAuthenticator implements Authenticator {
     private String userName;
     private String password;
 
-    public BasicAuthenticator(@NonNull String userName, @NonNull String password) {
+    public BasicAuthenticator(String userName, String password) {
         this.userName = userName;
         this.password = password;
     }
 
     @Override
-    public Request authenticate(Route route, Response response) throws IOException {
+    public Request authenticate(Route route, Response response) {
         if (response.request().header("Authorization") != null) {
             return null; // Give up, we've already attempted to authenticate.
         }
diff --git a/src/main/java/com/thegrizzlylabs/sardineandroid/impl/OkHttpSardine.java b/src/main/java/com/thegrizzlylabs/sardineandroid/impl/OkHttpSardine.java
index 9e82204..dac1a4e 100644
--- a/src/main/java/com/thegrizzlylabs/sardineandroid/impl/OkHttpSardine.java
+++ b/src/main/java/com/thegrizzlylabs/sardineandroid/impl/OkHttpSardine.java
@@ -1,7 +1,5 @@
 package com.thegrizzlylabs.sardineandroid.impl;
 
-import android.support.annotation.NonNull;
-
 import com.thegrizzlylabs.sardineandroid.DavAce;
 import com.thegrizzlylabs.sardineandroid.DavAcl;
 import com.thegrizzlylabs.sardineandroid.DavPrincipal;
@@ -98,13 +96,13 @@ private class AuthenticationInterceptor implements Interceptor {
         private String userName;
         private String password;
 
-        public AuthenticationInterceptor(@NonNull String userName, @NonNull String password) {
+        public AuthenticationInterceptor(String userName, String password) {
             this.userName = userName;
             this.password = password;
         }
 
         @Override
-        public Response intercept(@NonNull Chain chain) throws IOException {
+        public Response intercept(Chain chain) throws IOException {
             Request request = chain.request().newBuilder().addHeader("Authorization", Credentials.basic(userName, password)).build();
             return chain.proceed(request);
         }
@@ -317,7 +315,7 @@ private void put(String url, RequestBody requestBody) throws IOException {
         put(url, requestBody, new Headers.Builder().build());
     }
 
-    private void put(String url, RequestBody requestBody, @NonNull Headers headers) throws IOException {
+    private void put(String url, RequestBody requestBody, Headers headers) throws IOException {
         Request request = new Request.Builder()
                 .url(url)
                 .put(requestBody)