diff --git a/service/src/main/kotlin/org/microg/nlp/service/AbstractBackendHelper.kt b/service/src/main/kotlin/org/microg/nlp/service/AbstractBackendHelper.kt
index 5e4646a..ad00475 100644
--- a/service/src/main/kotlin/org/microg/nlp/service/AbstractBackendHelper.kt
+++ b/service/src/main/kotlin/org/microg/nlp/service/AbstractBackendHelper.kt
@@ -67,7 +67,7 @@ abstract class AbstractBackendHelper(private val TAG: String, private val contex
                 Log.w(TAG, "Intent is not properly resolved, can't verify signature. Aborting.")
                 return
             }
-            val computedDigest = firstSignatureDigest(context, serviceIntent.getPackage(), if (signatureDigest?.length == 40) "SHA-1" else "SHA-256")
+            val computedDigest = firstSignatureDigest(context, serviceIntent.getPackage(), "SHA-256")
             if (signatureDigest != null && signatureDigest != computedDigest) {
                 Log.w(TAG, "Target signature does not match selected package ($signatureDigest != $computedDigest). Aborting.")
                 return
diff --git a/service/src/main/kotlin/org/microg/nlp/service/Preferences.kt b/service/src/main/kotlin/org/microg/nlp/service/Preferences.kt
index 9217220..15733ab 100644
--- a/service/src/main/kotlin/org/microg/nlp/service/Preferences.kt
+++ b/service/src/main/kotlin/org/microg/nlp/service/Preferences.kt
@@ -53,13 +53,42 @@ class Preferences(private val context: Context) {
     }
 
     private fun getStringSetFromAny(key: String): Set<String>? {
+        migratePreference(key)
         val fromNewSettings = preferences.getStringSetCompat(key)
         if (fromNewSettings != null) return fromNewSettings
-        val fromOldSettings = oldPreferences.getStringSetCompat(key)
-        if (fromOldSettings != null) return fromOldSettings
         return systemDefaultPreferences?.getStringSetCompat(key)
     }
 
+    private fun migratePreference(key: String): Set<String>? {
+        val fromOldSettings = oldPreferences.getStringSetCompat(key)
+        if (fromOldSettings != null) {
+            var newSettings: MutableSet<String> = mutableSetOf<String>()
+            for (oldBackend in fromOldSettings) {
+                // Get package name and sha1
+                val parts = oldBackend.split("/".toRegex()).dropLastWhile(String::isEmpty).toTypedArray()
+                if (parts.size < 3) continue // skip unsigned
+                val pkgName = parts[0]
+                val component = parts[1]
+                val oldSig = parts[2]
+                if (oldSig?.length != 40) continue // skip if not sha1
+                // Get matching sha256
+                val sha1 = AbstractBackendHelper.firstSignatureDigest(context, pkgName, "SHA-1")
+                val sha256 = AbstractBackendHelper.firstSignatureDigest(context, pkgName, "SHA-256")
+                // If the system sha1 matches what we had stored
+                if (oldSig == sha1) {
+                    // Replace it with the sha256
+                    val newBackend = "${pkgName}/${component}/${sha256}"
+                    newSettings.add(newBackend)
+                }
+            }
+             if (preferences.edit().putStringSetCompat(key, newSettings.toSet()).commit()) {
+                 // Only delete the old preference once committed.
+                 oldPreferences.edit().remove(key).apply()
+             }
+        }
+        return null
+    }
+
     var locationBackends: Set<String>
         get() = getStringSetFromAny(PREF_LOCATION_BACKENDS) ?: emptySet()
         set(backends) {