diff --git a/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager.java b/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager.java
index 251310c50..3364251c6 100644
--- a/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager.java
@@ -3,6 +3,7 @@ package org.briarproject.briar.android.hotspot;
 import android.provider.Settings;
 
 import org.briarproject.briar.R;
+import org.briarproject.nullsafety.NotNullByDefault;
 
 import java.util.logging.Logger;
 
@@ -18,6 +19,7 @@ import static java.util.logging.Logger.getLogger;
  * As soon as {@link #checkAndRequestConditions()} returns true,
  * all conditions are fulfilled.
  */
+@NotNullByDefault
 class ConditionManager extends AbstractConditionManager {
 
 	private static final Logger LOG =
diff --git a/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager29.java b/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager29.java
index 381d0a694..547a44e92 100644
--- a/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager29.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager29.java
@@ -5,6 +5,7 @@ import android.provider.Settings;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.util.Permission;
 import org.briarproject.briar.android.util.PermissionUtils;
+import org.briarproject.nullsafety.NotNullByDefault;
 
 import java.util.logging.Logger;
 
@@ -32,6 +33,7 @@ import static org.briarproject.briar.android.util.PermissionUtils.showLocationDi
  * all conditions are fulfilled.
  */
 @RequiresApi(29)
+@NotNullByDefault
 class ConditionManager29 extends AbstractConditionManager {
 
 	private static final Logger LOG =
diff --git a/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager33.java b/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager33.java
index f33427338..89cf62e2b 100644
--- a/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager33.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/hotspot/ConditionManager33.java
@@ -5,6 +5,7 @@ import android.provider.Settings;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.util.Permission;
 import org.briarproject.briar.android.util.PermissionUtils;
+import org.briarproject.nullsafety.NotNullByDefault;
 
 import java.util.logging.Logger;
 
@@ -29,6 +30,7 @@ import static java.util.logging.Logger.getLogger;
  * all conditions are fulfilled.
  */
 @RequiresApi(33)
+@NotNullByDefault
 class ConditionManager33 extends AbstractConditionManager {
 
 	private static final Logger LOG =