diff --git a/src/main/kotlin/app/morphe/cli/command/PatchCommand.kt b/src/main/kotlin/app/morphe/cli/command/PatchCommand.kt
index 80432c6..4f74c7c 100644
--- a/src/main/kotlin/app/morphe/cli/command/PatchCommand.kt
+++ b/src/main/kotlin/app/morphe/cli/command/PatchCommand.kt
@@ -19,13 +19,23 @@ import app.morphe.cli.command.model.mergeWith
 import app.morphe.cli.command.model.toPatchBundle
 import app.morphe.cli.command.model.toSerializablePatch
 import app.morphe.cli.command.model.withUpdatedBundle
+import app.morphe.engine.PatchEngine
+import app.morphe.engine.PatchEngine.Config.Companion.DEFAULT_KEYSTORE_ALIAS
+import app.morphe.engine.PatchEngine.Config.Companion.DEFAULT_KEYSTORE_PASSWORD
+import app.morphe.engine.PatchEngine.Config.Companion.LEGACY_KEYSTORE_ALIAS
+import app.morphe.engine.PatchEngine.Config.Companion.LEGACY_KEYSTORE_PASSWORD
 import app.morphe.engine.UpdateChecker
-import app.morphe.patcher.apk.ApkUtils
-import app.morphe.patcher.apk.ApkUtils.applyTo
-import app.morphe.library.installation.installer.*
+import app.morphe.library.installation.installer.AdbInstaller
+import app.morphe.library.installation.installer.AdbInstallerResult
+import app.morphe.library.installation.installer.AdbRootInstaller
+import app.morphe.library.installation.installer.DeviceNotFoundException
+import app.morphe.library.installation.installer.Installer
+import app.morphe.library.installation.installer.RootInstallerResult
 import app.morphe.patcher.Patcher
 import app.morphe.patcher.PatcherConfig
 import app.morphe.patcher.apk.ApkMerger
+import app.morphe.patcher.apk.ApkUtils
+import app.morphe.patcher.apk.ApkUtils.applyTo
 import app.morphe.patcher.logging.toMorpheLogger
 import app.morphe.patcher.patch.Patch
 import app.morphe.patcher.patch.loadPatchesFromJar
@@ -196,13 +206,13 @@ internal object PatchCommand : Callable<Int> {
         description = ["Alias of the private key and certificate pair keystore entry."],
         showDefaultValue = ALWAYS,
     )
-    private var keyStoreEntryAlias = "Morphe Key"
+    private var keyStoreEntryAlias = PatchEngine.Config.DEFAULT_KEYSTORE_ALIAS
 
     @CommandLine.Option(
         names = ["--keystore-entry-password"],
         description = ["Password of the keystore entry."],
     )
-    private var keyStoreEntryPassword = "" // Empty password by default
+    private var keyStoreEntryPassword = PatchEngine.Config.DEFAULT_KEYSTORE_PASSWORD
 
     @CommandLine.Option(
         names = ["--signer"],
@@ -666,17 +676,34 @@ internal object PatchCommand : Callable<Int> {
                     patchingResult.addStepResult(
                         PatchingStep.SIGNING,
                         {
-                            ApkUtils.signApk(
-                                patchedApkFile,
-                                outputFilePath,
-                                signer,
-                                ApkUtils.KeyStoreDetails(
-                                    keystoreFilePath,
-                                    keyStorePassword,
-                                    keyStoreEntryAlias,
-                                    keyStoreEntryPassword,
-                                ),
-                            )
+                            fun signApk(alias: String, password: String) {
+                                ApkUtils.signApk(
+                                    patchedApkFile,
+                                    outputFilePath,
+                                    signer,
+                                    ApkUtils.KeyStoreDetails(
+                                        keystoreFilePath,
+                                        keyStorePassword,
+                                        alias,
+                                        password,
+                                    )
+                                )
+                            }
+                            try {
+                                signApk(keyStoreEntryAlias, keyStoreEntryPassword)
+                            } catch (e: Exception){
+                                // Retry with legacy keystore defaults.
+                                if (keyStoreEntryAlias == DEFAULT_KEYSTORE_ALIAS &&
+                                    keyStoreEntryPassword == DEFAULT_KEYSTORE_PASSWORD &&
+                                    keystoreFilePath.exists()
+                                ) {
+                                    logger.info("Using legacy keystore credentials")
+
+                                    signApk(LEGACY_KEYSTORE_ALIAS, LEGACY_KEYSTORE_PASSWORD)
+                                } else {
+                                    throw e
+                                }
+                            }
                         }
                     )
                 } else {
diff --git a/src/main/kotlin/app/morphe/engine/PatchEngine.kt b/src/main/kotlin/app/morphe/engine/PatchEngine.kt
index d1d81fa..ec6c9fa 100644
--- a/src/main/kotlin/app/morphe/engine/PatchEngine.kt
+++ b/src/main/kotlin/app/morphe/engine/PatchEngine.kt
@@ -27,9 +27,11 @@ import java.io.StringWriter
 import java.nio.file.Files
 import java.util.logging.Logger
 
-/**
+/*
  * Single patching pipeline shared by CLI and GUI. (Eventually. Right now we are still having 2 pipelines)
  */
+
+
 object PatchEngine {
 
     enum class PatchStep {
@@ -54,7 +56,14 @@ object PatchEngine {
         val aaptBinaryPath: File? = null,
         val tempDir: File? = null,
         val failOnError: Boolean = true,
-    )
+    ) {
+        companion object {
+            internal const val DEFAULT_KEYSTORE_ALIAS = "Morphe"
+            internal const val DEFAULT_KEYSTORE_PASSWORD = "Morphe"
+            internal const val LEGACY_KEYSTORE_ALIAS = "Morphe Key"
+            internal const val LEGACY_KEYSTORE_PASSWORD = ""
+        }
+    }
 
     data class Result(
         val success: Boolean,
@@ -215,18 +224,40 @@ object PatchEngine {
                 if (!config.unsigned) {
                     onProgress("Signing APK...")
                     try {
+                        fun signApk(details: ApkUtils.KeyStoreDetails) {
+                            ApkUtils.signApk(
+                                rebuiltApk,
+                                tempOutput,
+                                config.signerName,
+                                details,
+                            )
+                        }
+
                         val keystoreDetails = config.keystoreDetails ?: ApkUtils.KeyStoreDetails(
                             File(tempDir, "morphe.keystore"),
                             null,
-                            "Morphe Key",
-                            "",
-                        )
-                        ApkUtils.signApk(
-                            rebuiltApk,
-                            tempOutput,
-                            config.signerName,
-                            keystoreDetails,
+                            Config.DEFAULT_KEYSTORE_ALIAS,
+                            Config.DEFAULT_KEYSTORE_PASSWORD,
                         )
+
+                        try {
+                            signApk(keystoreDetails)
+                        } catch (e: Exception){
+                            // Retry with legacy keystore defaults.
+                            if (config.keystoreDetails == null && keystoreDetails.keyStore.exists()) {
+                                logger.info("Using legacy keystore credentials")
+
+                                val legacyKeystoreDetails = ApkUtils.KeyStoreDetails(
+                                    keystoreDetails.keyStore,
+                                    null,
+                                    Config.LEGACY_KEYSTORE_ALIAS,
+                                    Config.LEGACY_KEYSTORE_PASSWORD,
+                                )
+                                signApk(legacyKeystoreDetails)
+                            } else {
+                                throw e
+                            }
+                        }
                         stepResults.add(StepResult(PatchStep.SIGNING, true))
                     } catch (e: Exception) {
                         stepResults.add(StepResult(PatchStep.SIGNING, false, e.toString()))