diff --git a/MIDIDriver/build.gradle b/MIDIDriver/build.gradle
index 77bab7c..d2434b5 100644
--- a/MIDIDriver/build.gradle
+++ b/MIDIDriver/build.gradle
@@ -51,6 +51,21 @@ android {
         release.setRoot('build-types/release')
     }
 
+    defaultConfig {
+        consumerProguardFiles 'proguard-rules.pro'
+    }
+
+    buildTypes {
+        debug {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+        release {
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+
     publishing {
         singleVariant('release') {
             withSourcesJar()
diff --git a/MIDIDriver/proguard-rules.pro b/MIDIDriver/proguard-rules.pro
new file mode 100644
index 0000000..99a1099
--- /dev/null
+++ b/MIDIDriver/proguard-rules.pro
@@ -0,0 +1,32 @@
+-keep public class jp.kshoji.driver.midi.** {
+    public protected *;
+}
+-keep public class jp.kshoji.driver.usb.util.** {
+    public protected *;
+}
+-keep public class jp.kshoji.javax.sound.midi.** {
+    public protected *;
+}
+-keep public class jp.kshoji.unity.midi.** {
+    public protected *;
+}
+
+-keepparameternames
+-renamesourcefileattribute SourceFile
+-keepattributes Signature,Exceptions,*Annotation*,
+                InnerClasses,PermittedSubclasses,EnclosingMethod,
+                Deprecated,SourceFile,LineNumberTable
+
+-keepclassmembers,allowoptimization enum * {
+    public static **[] values();
+    public static ** valueOf(java.lang.String);
+}
+
+-keepclassmembers class * implements java.io.Serializable {
+    static final long serialVersionUID;
+    private static final java.io.ObjectStreamField[] serialPersistentFields;
+    private void writeObject(java.io.ObjectOutputStream);
+    private void readObject(java.io.ObjectInputStream);
+    java.lang.Object writeReplace();
+    java.lang.Object readResolve();
+}
diff --git a/build.gradle b/build.gradle
index 109ff5e..e0b7d16 100644
--- a/build.gradle
+++ b/build.gradle
@@ -5,7 +5,7 @@ buildscript {
         mavenCentral()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:8.3.0'
+        classpath 'com.android.tools.build:gradle:8.3.1'
     }
 }