diff --git a/build.gradle b/build.gradle
index c7cdea5..3cc7fe8 100644
--- a/build.gradle
+++ b/build.gradle
@@ -17,12 +17,12 @@ repositories {
 
 dependencies {
     api 'com.google.code.findbugs:jsr305:2.0.1'
-    api 'com.google.guava:guava:17.0'
-    api 'org.apache.commons:commons-lang3:3.3.2'
+    api 'com.google.guava:guava:21.0'
+    api 'org.apache.commons:commons-lang3:3.5'
     testImplementation 'junit:junit-dep:4.10'
     testImplementation 'org.hamcrest:hamcrest-library:1.2.1'
     testImplementation 'org.mockito:mockito-core:1.8.5'
-    testImplementation 'com.google.guava:guava-testlib:17.0'
+    testImplementation 'com.google.guava:guava-testlib:21.0'
 }
 
 task sourcesJar(type: Jar) {