diff --git a/.idea/compiler.xml b/.idea/compiler.xml
index b589d56..b86273d 100644
--- a/.idea/compiler.xml
+++ b/.idea/compiler.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="CompilerConfiguration">
-    <bytecodeTargetLevel target="17" />
+    <bytecodeTargetLevel target="21" />
   </component>
 </project>
\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
index 2284611..b96734e 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -1,3 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ExternalStorageConfigurationManager" enabled="true" />
   <component name="NullableNotNullManager">
@@ -5,7 +6,7 @@
     <option name="myDefaultNotNull" value="androidx.annotation.NonNull" />
     <option name="myNullables">
       <value>
-        <list size="17">
+        <list size="18">
           <item index="0" class="java.lang.String" itemvalue="org.jetbrains.annotations.Nullable" />
           <item index="1" class="java.lang.String" itemvalue="javax.annotation.Nullable" />
           <item index="2" class="java.lang.String" itemvalue="javax.annotation.CheckForNull" />
@@ -23,12 +24,13 @@
           <item index="14" class="java.lang.String" itemvalue="io.reactivex.rxjava3.annotations.Nullable" />
           <item index="15" class="java.lang.String" itemvalue="org.jspecify.nullness.Nullable" />
           <item index="16" class="java.lang.String" itemvalue="jakarta.annotation.Nullable" />
+          <item index="17" class="java.lang.String" itemvalue="org.jspecify.annotations.Nullable" />
         </list>
       </value>
     </option>
     <option name="myNotNulls">
       <value>
-        <list size="16">
+        <list size="17">
           <item index="0" class="java.lang.String" itemvalue="org.jetbrains.annotations.NotNull" />
           <item index="1" class="java.lang.String" itemvalue="javax.annotation.Nonnull" />
           <item index="2" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.NonNull" />
@@ -45,11 +47,12 @@
           <item index="13" class="java.lang.String" itemvalue="io.reactivex.rxjava3.annotations.NonNull" />
           <item index="14" class="java.lang.String" itemvalue="jakarta.annotation.Nonnull" />
           <item index="15" class="java.lang.String" itemvalue="org.jspecify.nullness.NonNull" />
+          <item index="16" class="java.lang.String" itemvalue="org.jspecify.annotations.NonNull" />
         </list>
       </value>
     </option>
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" default="true" project-jdk-name="jbr-17" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_21" default="true" project-jdk-name="jbr-21" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/build/classes" />
   </component>
   <component name="ProjectType">
diff --git a/.idea/runConfigurations.xml b/.idea/runConfigurations.xml
new file mode 100644
index 0000000..16660f1
--- /dev/null
+++ b/.idea/runConfigurations.xml
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="RunConfigurationProducerService">
+    <option name="ignoredProducers">
+      <set>
+        <option value="com.intellij.execution.junit.AbstractAllInDirectoryConfigurationProducer" />
+        <option value="com.intellij.execution.junit.AllInPackageConfigurationProducer" />
+        <option value="com.intellij.execution.junit.PatternConfigurationProducer" />
+        <option value="com.intellij.execution.junit.TestInClassConfigurationProducer" />
+        <option value="com.intellij.execution.junit.UniqueIdConfigurationProducer" />
+        <option value="com.intellij.execution.junit.testDiscovery.JUnitTestDiscoveryConfigurationProducer" />
+        <option value="org.jetbrains.kotlin.idea.junit.KotlinJUnitRunConfigurationProducer" />
+        <option value="org.jetbrains.kotlin.idea.junit.KotlinPatternConfigurationProducer" />
+      </set>
+    </option>
+  </component>
+</project>
\ No newline at end of file
diff --git a/build.gradle b/build.gradle
index 2754766..1b452cf 100644
--- a/build.gradle
+++ b/build.gradle
@@ -6,7 +6,7 @@ buildscript {
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:8.4.0'
+        classpath 'com.android.tools.build:gradle:8.7.3'
     }
 }
 
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 3ae3347..9a0de51 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.6-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.9-all.zip
diff --git a/usbSerialExamples/build.gradle b/usbSerialExamples/build.gradle
index f8e718b..a728752 100644
--- a/usbSerialExamples/build.gradle
+++ b/usbSerialExamples/build.gradle
@@ -28,6 +28,6 @@ android {
 
 dependencies {
     implementation project(':usbSerialForAndroid')
-    implementation 'androidx.appcompat:appcompat:1.6.1'
-    implementation 'com.google.android.material:material:1.11.0'
+    implementation 'androidx.appcompat:appcompat:1.6.1' // later versions have minsdk 21
+    implementation 'com.google.android.material:material:1.11.0' // later versions have minsdk 19
 }
diff --git a/usbSerialForAndroid/build.gradle b/usbSerialForAndroid/build.gradle
index 06ad81f..f2b3ccc 100644
--- a/usbSerialForAndroid/build.gradle
+++ b/usbSerialForAndroid/build.gradle
@@ -31,13 +31,13 @@ android {
 }
 
 dependencies {
-    implementation "androidx.annotation:annotation:1.8.0"
+    implementation "androidx.annotation:annotation:1.9.1"
     testImplementation 'junit:junit:4.13.2'
-    testImplementation 'org.mockito:mockito-core:5.12.0'
-    androidTestImplementation 'androidx.appcompat:appcompat:1.6.1'
-    androidTestImplementation 'androidx.test:core:1.5.0'
-    androidTestImplementation 'androidx.test:runner:1.5.2'
-    androidTestImplementation 'commons-net:commons-net:3.9.0' // later version fails on old Android devices with missing java.time.Duration class
+    testImplementation 'org.mockito:mockito-core:5.15.2'
+    androidTestImplementation 'androidx.appcompat:appcompat:1.6.1' // later versions have minsdk 21
+    androidTestImplementation 'androidx.test:core:1.5.0' // later versions have minsdk 19
+    androidTestImplementation 'androidx.test:runner:1.5.2' // later versions have minsdk 19
+    androidTestImplementation 'commons-net:commons-net:3.9.0' // later versions fail on old Android devices with missing java.time.Duration class
     androidTestImplementation 'org.apache.commons:commons-lang3:3.14.0'
 }