diff --git a/oeffi/AndroidManifest.xml b/oeffi/AndroidManifest.xml
index 0986153..ac194ca 100644
--- a/oeffi/AndroidManifest.xml
+++ b/oeffi/AndroidManifest.xml
@@ -24,7 +24,7 @@
     android:versionName="12.1.21">
 
     <uses-sdk
-        android:minSdkVersion="21"
+        android:minSdkVersion="24"
         android:targetSdkVersion="34" />
 
     <uses-permission android:name="android.permission.INTERNET" />
diff --git a/oeffi/src/de/schildbach/oeffi/OeffiActivity.java b/oeffi/src/de/schildbach/oeffi/OeffiActivity.java
index 04c5e2b..a4f76a1 100644
--- a/oeffi/src/de/schildbach/oeffi/OeffiActivity.java
+++ b/oeffi/src/de/schildbach/oeffi/OeffiActivity.java
@@ -17,12 +17,10 @@
 
 package de.schildbach.oeffi;
 
-import android.annotation.TargetApi;
 import android.app.ActivityManager.TaskDescription;
 import android.content.SharedPreferences;
 import android.content.res.Resources;
 import android.graphics.drawable.Drawable;
-import android.os.Build;
 import android.os.Bundle;
 import android.preference.PreferenceManager;
 import android.text.format.DateUtils;
@@ -152,10 +150,4 @@ public abstract class OeffiActivity extends ComponentActivity {
 
         return str;
     }
-
-    @TargetApi(24)
-    @Override
-    public boolean isInMultiWindowMode() {
-        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.N && super.isInMultiWindowMode();
-    }
 }
diff --git a/oeffi/src/de/schildbach/oeffi/network/NetworkPickerActivity.java b/oeffi/src/de/schildbach/oeffi/network/NetworkPickerActivity.java
index f18c129..ba5c8fd 100644
--- a/oeffi/src/de/schildbach/oeffi/network/NetworkPickerActivity.java
+++ b/oeffi/src/de/schildbach/oeffi/network/NetworkPickerActivity.java
@@ -18,7 +18,6 @@
 package de.schildbach.oeffi.network;
 
 import android.Manifest;
-import android.annotation.TargetApi;
 import android.app.ActivityManager.TaskDescription;
 import android.content.Context;
 import android.content.Intent;
@@ -29,7 +28,6 @@ import android.content.res.Resources;
 import android.location.Address;
 import android.location.Criteria;
 import android.location.LocationManager;
-import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.HandlerThread;
@@ -571,10 +569,4 @@ public class NetworkPickerActivity extends ComponentActivity implements Location
         actionBar.setBackgroundColor(color);
         setTaskDescription(new TaskDescription(null, null, color));
     }
-
-    @TargetApi(24)
-    @Override
-    public boolean isInMultiWindowMode() {
-        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.N && super.isInMultiWindowMode();
-    }
 }
diff --git a/oeffi/src/de/schildbach/oeffi/preference/CommonFragment.java b/oeffi/src/de/schildbach/oeffi/preference/CommonFragment.java
index cd73015..9486a15 100644
--- a/oeffi/src/de/schildbach/oeffi/preference/CommonFragment.java
+++ b/oeffi/src/de/schildbach/oeffi/preference/CommonFragment.java
@@ -17,7 +17,6 @@
 
 package de.schildbach.oeffi.preference;
 
-import android.os.Build;
 import android.os.Bundle;
 import android.preference.PreferenceFragment;
 import de.schildbach.oeffi.R;
@@ -25,13 +24,11 @@ import de.schildbach.oeffi.R;
 import javax.annotation.Nullable;
 
 public class CommonFragment extends PreferenceFragment {
-    private static final String KEY_BATTERY_OPTIMIZATIONS = "battery_optimizations";
 
     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
         addPreferencesFromResource(R.xml.preference_common);
-        findPreference(KEY_BATTERY_OPTIMIZATIONS).setEnabled(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M);
     }
 }
diff --git a/oeffi/src/de/schildbach/oeffi/util/ErrorReporter.java b/oeffi/src/de/schildbach/oeffi/util/ErrorReporter.java
index a7cc80a..cbc90ce 100644
--- a/oeffi/src/de/schildbach/oeffi/util/ErrorReporter.java
+++ b/oeffi/src/de/schildbach/oeffi/util/ErrorReporter.java
@@ -181,8 +181,7 @@ public class ErrorReporter implements Thread.UncaughtExceptionHandler {
         report.append("Manufacturer: " + Build.MANUFACTURER + "\n");
         report.append("Phone Model: " + Build.MODEL + "\n");
         report.append("Android Version: " + Build.VERSION.RELEASE + "\n");
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
-            report.append("Android security patch level: ").append(Build.VERSION.SECURITY_PATCH).append("\n");
+        report.append("Android security patch level: ").append(Build.VERSION.SECURITY_PATCH).append("\n");
         report.append("ABIs: ").append(Joiner.on(", ").skipNulls().join(Strings.emptyToNull(Build.CPU_ABI),
                 Strings.emptyToNull(Build.CPU_ABI2))).append("\n");
         report.append("Board: " + Build.BOARD + "\n");