diff --git a/app/src/main/java/com/stevesoltys/seedvault/crypto/Crypto.kt b/app/src/main/java/com/stevesoltys/seedvault/crypto/Crypto.kt
index d859e91d..05a1e869 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/crypto/Crypto.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/crypto/Crypto.kt
@@ -87,7 +87,9 @@ class CryptoImpl(
     override fun encryptSegment(outputStream: OutputStream, cleartext: ByteArray) {
         val cipher = cipherFactory.createEncryptionCipher()
 
-        check(cipher.getOutputSize(cleartext.size) <= MAX_SEGMENT_LENGTH)
+        check(cipher.getOutputSize(cleartext.size) <= MAX_SEGMENT_LENGTH) {
+            "Cipher's output size ${cipher.getOutputSize(cleartext.size)} is larger than maximum segment length ($MAX_SEGMENT_LENGTH)"
+        }
 
         val encrypted = cipher.doFinal(cleartext)
         val segmentHeader = SegmentHeader(encrypted.size.toShort(), cipher.iv)
diff --git a/app/src/main/java/com/stevesoltys/seedvault/header/Header.kt b/app/src/main/java/com/stevesoltys/seedvault/header/Header.kt
index 864acd03..6a71bfe7 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/header/Header.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/header/Header.kt
@@ -15,8 +15,12 @@ data class VersionHeader(
         internal val key: String? = null      // ?? bytes
 ) {
     init {
-        check(packageName.length <= MAX_PACKAGE_LENGTH_SIZE)
-        key?.let { check(key.length <= MAX_KEY_LENGTH_SIZE) }
+        check(packageName.length <= MAX_PACKAGE_LENGTH_SIZE) {
+            "Package $packageName has name longer than $MAX_PACKAGE_LENGTH_SIZE"
+        }
+        key?.let {
+            check(key.length <= MAX_KEY_LENGTH_SIZE) { "Key $key is longer than $MAX_KEY_LENGTH_SIZE" }
+        }
     }
 }
 
@@ -34,6 +38,8 @@ class SegmentHeader(
         internal val nonce: ByteArray         // 12 bytes
 ) {
     init {
-        check(nonce.size == IV_SIZE)
+        check(nonce.size == IV_SIZE) {
+            "Nonce size of ${nonce.size} is not the expected IV size of $IV_SIZE"
+        }
     }
 }
diff --git a/app/src/main/java/com/stevesoltys/seedvault/restore/RestoreViewModel.kt b/app/src/main/java/com/stevesoltys/seedvault/restore/RestoreViewModel.kt
index 3549aa63..47fd3ad8 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/restore/RestoreViewModel.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/restore/RestoreViewModel.kt
@@ -62,7 +62,7 @@ class RestoreViewModel(app: Application) : RequireProvisioningViewModel(app), Re
 
     override fun onRestoreSetClicked(set: RestoreSet) {
         val session = this.session
-        check(session != null)
+        check(session != null) { "Restore set clicked, but no session available" }
         session.restoreAll(set.token, observer, monitor)
 
         mChosenRestoreSet.value = set
diff --git a/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsManager.kt b/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsManager.kt
index a1f2d7a7..4a654b56 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsManager.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/settings/SettingsManager.kt
@@ -35,7 +35,7 @@ class SettingsManager(context: Context) {
     fun getStorage(): Storage? {
         val uriStr = prefs.getString(PREF_KEY_STORAGE_URI, null) ?: return null
         val uri = Uri.parse(uriStr)
-        val name = prefs.getString(PREF_KEY_STORAGE_NAME, null) ?: throw IllegalStateException()
+        val name = prefs.getString(PREF_KEY_STORAGE_NAME, null) ?: throw IllegalStateException("no storage name")
         val isUsb = prefs.getBoolean(PREF_KEY_STORAGE_IS_USB, false)
         return Storage(uri, name, isUsb)
     }
diff --git a/app/src/main/java/com/stevesoltys/seedvault/transport/ConfigurableBackupTransportService.kt b/app/src/main/java/com/stevesoltys/seedvault/transport/ConfigurableBackupTransportService.kt
index c6b8ec52..9d4ef7a8 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/transport/ConfigurableBackupTransportService.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/transport/ConfigurableBackupTransportService.kt
@@ -33,7 +33,7 @@ class ConfigurableBackupTransportService : Service() {
     }
 
     override fun onBind(intent: Intent): IBinder {
-        val transport = this.transport ?: throw IllegalStateException()
+        val transport = this.transport ?: throw IllegalStateException("no transport in onBind()")
         return transport.binder.apply {
             Log.d(TAG, "Transport bound.")
         }
diff --git a/app/src/main/java/com/stevesoltys/seedvault/transport/backup/BackupCoordinator.kt b/app/src/main/java/com/stevesoltys/seedvault/transport/backup/BackupCoordinator.kt
index 857bf0ee..ab7911aa 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/transport/backup/BackupCoordinator.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/transport/backup/BackupCoordinator.kt
@@ -178,11 +178,11 @@ class BackupCoordinator(
 
     fun finishBackup(): Int = when {
         kv.hasState() -> {
-            check(!full.hasState())
+            check(!full.hasState()) { "K/V backup has state, but full backup has dangling state as well" }
             kv.finishBackup()
         }
         full.hasState() -> {
-            check(!kv.hasState())
+            check(!kv.hasState()) { "Full backup has state, but K/V backup has dangling state as well" }
             full.finishBackup()
         }
         calledInitialize || calledClearBackupData -> {
@@ -190,7 +190,7 @@ class BackupCoordinator(
             calledClearBackupData = false
             TRANSPORT_OK
         }
-        else -> throw IllegalStateException()
+        else -> throw IllegalStateException("Unexpected state in finishBackup()")
     }
 
     @Throws(IOException::class)
diff --git a/app/src/main/java/com/stevesoltys/seedvault/transport/restore/FullRestore.kt b/app/src/main/java/com/stevesoltys/seedvault/transport/restore/FullRestore.kt
index 17905fed..ce8d40cc 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/transport/restore/FullRestore.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/transport/restore/FullRestore.kt
@@ -77,7 +77,7 @@ internal class FullRestore(
      */
     fun getNextFullRestoreDataChunk(socket: ParcelFileDescriptor): Int {
         Log.i(TAG, "Get next full restore data chunk.")
-        val state = this.state ?: throw IllegalStateException()
+        val state = this.state ?: throw IllegalStateException("no state")
         val packageName = state.packageInfo.packageName
 
         if (state.inputStream == null) {
@@ -103,9 +103,9 @@ internal class FullRestore(
     }
 
     private fun readInputStream(socket: ParcelFileDescriptor): Int = socket.use { fileDescriptor ->
-        val state = this.state ?: throw IllegalStateException()
+        val state = this.state ?: throw IllegalStateException("no state")
         val packageName = state.packageInfo.packageName
-        val inputStream = state.inputStream ?: throw IllegalStateException()
+        val inputStream = state.inputStream ?: throw IllegalStateException("no stream")
         val outputStream = outputFactory.getOutputStream(fileDescriptor)
 
         try {
@@ -144,7 +144,7 @@ internal class FullRestore(
      * with no further attempts to restore app data.
      */
     fun abortFullRestore(): Int {
-        val state = this.state ?: throw IllegalStateException()
+        val state = this.state ?: throw IllegalStateException("no state")
         Log.i(TAG, "Abort full restore of ${state.packageInfo.packageName}!")
 
         resetState()
@@ -156,7 +156,7 @@ internal class FullRestore(
      * freeing any resources and connections used during the restore process.
      */
     fun finishRestore() {
-        val state = this.state ?: throw IllegalStateException()
+        val state = this.state ?: throw IllegalStateException("no state")
         Log.i(TAG, "Finish restore of ${state.packageInfo.packageName}!")
 
         resetState()
diff --git a/app/src/main/java/com/stevesoltys/seedvault/transport/restore/KVRestore.kt b/app/src/main/java/com/stevesoltys/seedvault/transport/restore/KVRestore.kt
index 0ea2b611..cd24e02d 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/transport/restore/KVRestore.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/transport/restore/KVRestore.kt
@@ -55,7 +55,7 @@ internal class KVRestore(
      * or [TRANSPORT_ERROR] (an error occurred, the restore should be aborted and rescheduled).
      */
     fun getRestoreData(data: ParcelFileDescriptor): Int {
-        val state = this.state ?: throw IllegalStateException()
+        val state = this.state ?: throw IllegalStateException("no state")
 
         // The restore set is the concatenation of the individual record blobs,
         // each of which is a file in the package's directory.
diff --git a/app/src/main/java/com/stevesoltys/seedvault/transport/restore/RestoreCoordinator.kt b/app/src/main/java/com/stevesoltys/seedvault/transport/restore/RestoreCoordinator.kt
index 75ea3a24..ba4f583e 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/transport/restore/RestoreCoordinator.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/transport/restore/RestoreCoordinator.kt
@@ -43,7 +43,9 @@ internal class RestoreCoordinator(
         val restoreSets = ArrayList<RestoreSet>()
         for (encryptedMetadata in availableBackups) {
             if (encryptedMetadata.error) continue
-            check(encryptedMetadata.inputStream != null)  // if there's no error, there must be a stream
+            check(encryptedMetadata.inputStream != null) {
+                "No error when getting encrypted metadata, but stream is still missing."
+            }
             try {
                 val metadata = metadataReader.readMetadata(encryptedMetadata.inputStream, encryptedMetadata.token)
                 val set = RestoreSet(metadata.deviceName, metadata.deviceName, metadata.token)
@@ -93,7 +95,7 @@ internal class RestoreCoordinator(
      * or [TRANSPORT_ERROR] (an error occurred, the restore should be aborted and rescheduled).
      */
     fun startRestore(token: Long, packages: Array<out PackageInfo>): Int {
-        check(state == null)
+        check(state == null) { "Started new restore with existing state" }
         Log.i(TAG, "Start restore with ${packages.map { info -> info.packageName }}")
         state = RestoreCoordinatorState(token, packages.iterator())
         return TRANSPORT_OK
@@ -127,7 +129,7 @@ internal class RestoreCoordinator(
      */
     fun nextRestorePackage(): RestoreDescription? {
         Log.i(TAG, "Next restore package!")
-        val state = this.state ?: throw IllegalStateException()
+        val state = this.state ?: throw IllegalStateException("no state")
 
         if (!state.packages.hasNext()) return NO_MORE_PACKAGES
         val packageInfo = state.packages.next()
diff --git a/app/src/main/java/com/stevesoltys/seedvault/ui/storage/StorageViewModel.kt b/app/src/main/java/com/stevesoltys/seedvault/ui/storage/StorageViewModel.kt
index 60d38376..3a373649 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/ui/storage/StorageViewModel.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/ui/storage/StorageViewModel.kt
@@ -87,7 +87,7 @@ internal abstract class StorageViewModel(private val app: Application) : Android
      */
     protected fun saveStorage(uri: Uri): Boolean {
         // store backup storage location in settings
-        val root = storageRoot ?: throw IllegalStateException()
+        val root = storageRoot ?: throw IllegalStateException("no storage root")
         val name = if (root.isInternal()) {
             "${root.title} (${app.getString(R.string.settings_backup_location_internal)})"
         } else {