diff --git a/app/src/main/kotlin/dev/privacyllc/period/feature/lock/LockSettingsViewModel.kt b/app/src/main/kotlin/dev/privacyllc/period/feature/lock/LockSettingsViewModel.kt
index 171ccbc..750f6e2 100644
--- a/app/src/main/kotlin/dev/privacyllc/period/feature/lock/LockSettingsViewModel.kt
+++ b/app/src/main/kotlin/dev/privacyllc/period/feature/lock/LockSettingsViewModel.kt
@@ -76,7 +76,7 @@ class LockSettingsViewModel @Inject constructor(
         _busy.value = true
         viewModelScope.launch(handler) {
             val ok = lock.setPin(pin)
-            pin.fill(' ')
+            pin.fill('\u0000')
             // Stay unlocked in the session that just set the PIN. Without this
             // the gate flips shut the instant `hasPin` turns true, and the user
             // is asked for a PIN one second after choosing it — which reads as
@@ -101,7 +101,7 @@ class LockSettingsViewModel @Inject constructor(
         _busy.value = true
         viewModelScope.launch(handler) {
             val outcome = lock.check(pin)
-            pin.fill(' ')
+            pin.fill('\u0000')
             if (outcome is UnlockResult.Unlocked) {
                 onVerified()
                 _busy.value = false
diff --git a/app/src/main/kotlin/dev/privacyllc/period/lock/AppLockViewModel.kt b/app/src/main/kotlin/dev/privacyllc/period/lock/AppLockViewModel.kt
index 1ecced0..f353a78 100644
Binary files a/app/src/main/kotlin/dev/privacyllc/period/lock/AppLockViewModel.kt and b/app/src/main/kotlin/dev/privacyllc/period/lock/AppLockViewModel.kt differ