diff --git a/app/src/main/java/org/fdroid/fdroid/data/NewRepoConfig.java b/app/src/main/java/org/fdroid/fdroid/data/NewRepoConfig.java
index 099b0ff82..71c16b022 100644
--- a/app/src/main/java/org/fdroid/fdroid/data/NewRepoConfig.java
+++ b/app/src/main/java/org/fdroid/fdroid/data/NewRepoConfig.java
@@ -10,6 +10,7 @@ import org.fdroid.fdroid.R;
 import org.fdroid.fdroid.Utils;
 import org.fdroid.fdroid.nearby.SwapWorkflowActivity;
 import org.fdroid.fdroid.nearby.peers.WifiPeer;
+import org.fdroid.fdroid.views.ManageReposActivity;
 
 import java.util.Arrays;
 import java.util.List;
@@ -50,6 +51,12 @@ public class NewRepoConfig {
             return;
         }
 
+        if (ManageReposActivity.hasDisallowInstallUnknownSources(context)) {
+            errorMessage = ManageReposActivity.getDisallowInstallUnknownSourcesErrorMessage(context);
+            isValidRepo = false;
+            return;
+        }
+
         Utils.debugLog(TAG, "Parsing incoming intent looking for repo: " + incomingUri);
 
         // scheme and host should only ever be pure ASCII aka Locale.ENGLISH
diff --git a/app/src/main/java/org/fdroid/fdroid/views/ManageReposActivity.java b/app/src/main/java/org/fdroid/fdroid/views/ManageReposActivity.java
index 0db904c8a..9560c7edb 100644
--- a/app/src/main/java/org/fdroid/fdroid/views/ManageReposActivity.java
+++ b/app/src/main/java/org/fdroid/fdroid/views/ManageReposActivity.java
@@ -33,6 +33,7 @@ import android.net.wifi.WifiInfo;
 import android.net.wifi.WifiManager;
 import android.os.Build;
 import android.os.Bundle;
+import android.os.UserManager;
 import android.text.Editable;
 import android.text.TextUtils;
 import android.text.TextWatcher;
@@ -194,7 +195,11 @@ public class ManageReposActivity extends AppCompatActivity
     @Override
     public void finish() {
         Intent ret = new Intent();
-        setResult(RESULT_OK, ret);
+        if (getIntent() != null && hasDisallowInstallUnknownSources(this)) {
+            setResult(RESULT_CANCELED, ret);
+        } else {
+            setResult(RESULT_OK, ret);
+        }
         super.finish();
     }
 
@@ -262,7 +267,12 @@ public class ManageReposActivity extends AppCompatActivity
     }
 
     private void showAddRepo(String newAddress, String newFingerprint, String username, String password) {
-        new AddRepo(newAddress, newFingerprint, username, password);
+        if (hasDisallowInstallUnknownSources(this)) {
+            String msg = getDisallowInstallUnknownSourcesErrorMessage(this);
+            Toast.makeText(this, msg, Toast.LENGTH_LONG).show();
+        } else {
+            new AddRepo(newAddress, newFingerprint, username, password);
+        }
     }
 
     /**
@@ -911,4 +921,32 @@ public class ManageReposActivity extends AppCompatActivity
     private void notifyDataSetChanged() {
         getSupportLoaderManager().restartLoader(0, null, this);
     }
+
+    /**
+     * {@link android.app.admin.DevicePolicyManager} makes it possible to set
+     * user- or device-wide restrictions.  This changes whether installing from
+     * "Unknown Sources" has been disallowed by device policy.
+     *
+     * @return boolean whether installing from Unknown Sources has been disallowed
+     * @see UserManager#DISALLOW_INSTALL_UNKNOWN_SOURCES
+     * @see UserManager#DISALLOW_INSTALL_UNKNOWN_SOURCES_GLOBALLY
+     */
+    public static boolean hasDisallowInstallUnknownSources(Context context) {
+        UserManager userManager = (UserManager) context.getSystemService(Context.USER_SERVICE);
+        if (Build.VERSION.SDK_INT < 29) {
+            return userManager.hasUserRestriction(UserManager.DISALLOW_INSTALL_UNKNOWN_SOURCES);
+        } else {
+            return userManager.hasUserRestriction(UserManager.DISALLOW_INSTALL_UNKNOWN_SOURCES)
+                    || userManager.hasUserRestriction(UserManager.DISALLOW_INSTALL_UNKNOWN_SOURCES_GLOBALLY);
+        }
+    }
+
+    public static String getDisallowInstallUnknownSourcesErrorMessage(Context context) {
+        UserManager userManager = (UserManager) context.getSystemService(Context.USER_SERVICE);
+        if (Build.VERSION.SDK_INT >= 29
+                && userManager.hasUserRestriction(UserManager.DISALLOW_INSTALL_UNKNOWN_SOURCES_GLOBALLY)) {
+            return context.getString(R.string.has_disallow_install_unknown_sources_globally);
+        }
+        return context.getString(R.string.has_disallow_install_unknown_sources);
+    }
 }
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 0393d84dd..bbf57db48 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -197,6 +197,10 @@ This often occurs with apps installed via Google Play or other sources, if they
     <string name="bad_fingerprint">Bad fingerprint</string>
     <string name="invalid_url">This is not a valid URL.</string>
     <string name="malformed_repo_uri">Ignoring malformed repo URI: %s</string>
+    <!-- Message presented in a dialog box when the device-wide management policy restricts adding new repos, e.g. "Unknown Sources". -->
+    <string name="has_disallow_install_unknown_sources_globally">Your device admin doesn\'t allow installing apps from unknown sources, that includes new repos</string>
+    <!-- Message presented in a dialog box when the user restriction set by the system restricts adding new repos, e.g. "Unknown Sources". -->
+    <string name="has_disallow_install_unknown_sources">Unknown sources can\'t be added by this user, that includes new repos</string>
     <string name="repo_provider">Repository: %s</string>
 
     <string name="menu_manage">Repositories</string>