diff --git a/libgpsrelaysentinel/build.gradle b/libgpsrelaysentinel/build.gradle
index b11c04e..a047d86 100644
--- a/libgpsrelaysentinel/build.gradle
+++ b/libgpsrelaysentinel/build.gradle
@@ -9,7 +9,7 @@ android {
     buildToolsVersion "30.0.3"
 
     defaultConfig {
-        minSdkVersion 21
+        minSdkVersion 26
         targetSdkVersion 30
     }
     buildTypes {
@@ -18,6 +18,11 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_7
+        targetCompatibility JavaVersion.VERSION_1_7
+    }
 }
 
 dependencies {