diff --git a/lib/build.gradle b/lib/build.gradle
index 84480da0..e3700ab1 100644
--- a/lib/build.gradle
+++ b/lib/build.gradle
@@ -9,7 +9,7 @@ def home = System.properties['user.home']
 android {
     compileSdkVersion 26
     defaultConfig {
-        minSdkVersion 21
+        minSdkVersion 18
         targetSdkVersion 26
         versionCode 1
         versionName "1.0"