diff --git a/README.md b/README.md
index 5561ed48..872a8001 100644
--- a/README.md
+++ b/README.md
@@ -24,7 +24,7 @@ It uses the same internal APIs as `adb backup` which is deprecated and thus need
 * `android.permission.BACKUP` to back up application data.
 * `android.permission.MANAGE_DOCUMENTS` to retrieve the available storage roots. 
 * `android.permission.MANAGE_USB` to access the serial number of USB mass storage devices.
-* `android.permission.WRITE_SECURE_SETTINGS` to change system backup settings.
+* `android.permission.WRITE_SECURE_SETTINGS` to change system backup settings and enable call log backup.
 * `android.permission.INSTALL_PACKAGES` to re-install apps when restoring from backup.
 
 ## Contributing
diff --git a/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsFragment.kt b/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsFragment.kt
index 954cb9d0..5c0ad928 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsFragment.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsFragment.kt
@@ -70,6 +70,7 @@ class SettingsFragment : PreferenceFragmentCompat() {
             val enabled = newValue as Boolean
             try {
                 backupManager.isBackupEnabled = enabled
+                if (enabled) viewModel.enableCallLogBackup()
                 return@OnPreferenceChangeListener true
             } catch (e: RemoteException) {
                 e.printStackTrace()
@@ -171,6 +172,8 @@ class SettingsFragment : PreferenceFragmentCompat() {
         try {
             backup.isChecked = backupManager.isBackupEnabled
             backup.isEnabled = true
+            // enable call log backups for existing installs (added end of 2020)
+            if (backup.isChecked) viewModel.enableCallLogBackup()
         } catch (e: RemoteException) {
             Log.e(TAG, "Error communicating with BackupManager", e)
             backup.isEnabled = false
diff --git a/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsViewModel.kt b/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsViewModel.kt
index 02c30622..3b11506f 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsViewModel.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsViewModel.kt
@@ -2,6 +2,7 @@ package com.stevesoltys.seedvault.settings
 
 import android.app.Application
 import android.content.pm.PackageManager.NameNotFoundException
+import android.provider.Settings
 import android.util.Log
 import androidx.annotation.UiThread
 import androidx.core.content.ContextCompat.getDrawable
@@ -34,6 +35,8 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import java.util.Locale
 
+private const val USER_FULL_DATA_BACKUP_AWARE = "user_full_data_backup_aware"
+
 private val TAG = SettingsViewModel::class.java.simpleName
 
 internal class SettingsViewModel(
@@ -121,4 +124,18 @@ internal class SettingsViewModel(
         settingsManager.onAppBackupStatusChanged(status)
     }
 
+    /**
+     * Ensures that the call log will be included in backups.
+     *
+     * An AOSP code search found that call log backups get disabled if [USER_FULL_DATA_BACKUP_AWARE]
+     * is not set. This method sets this flag, if it is not already set.
+     * No other apps were found to check for this, so this should affect only call log.
+     */
+    fun enableCallLogBackup() {
+        // first check if the flag is already set
+        if (Settings.Secure.getInt(app.contentResolver, USER_FULL_DATA_BACKUP_AWARE, 0) == 0) {
+            Settings.Secure.putInt(app.contentResolver, USER_FULL_DATA_BACKUP_AWARE, 1)
+        }
+    }
+
 }