diff --git a/Sources/SwiftWhisper/Whisper.swift b/Sources/SwiftWhisper/Whisper.swift
index 07ffc81..bd74c04 100644
--- a/Sources/SwiftWhisper/Whisper.swift
+++ b/Sources/SwiftWhisper/Whisper.swift
@@ -45,7 +45,8 @@ public class Whisper {
         // swiftlint:disable line_length
         params.new_segment_callback = { (ctx: OpaquePointer?, _: OpaquePointer?, newSegmentCount: Int32, userData: UnsafeMutableRawPointer?) in
         // swiftlint:enable line_length
-            guard let ctx, let userData else { return }
+            guard let ctx = ctx,
+                  let userData = userData else { return }
             let whisper = Unmanaged<Whisper>.fromOpaque(userData).takeUnretainedValue()
             guard let delegate = whisper.delegate else { return }
 
@@ -73,7 +74,7 @@ public class Whisper {
         }
 
         params.encoder_begin_callback = { (_: OpaquePointer?, _: OpaquePointer?, userData: UnsafeMutableRawPointer?) in
-            guard let userData else { return true }
+            guard let userData = userData else { return true }
             let whisper = Unmanaged<Whisper>.fromOpaque(userData).takeUnretainedValue()
 
             if whisper.cancelCallback != nil {
@@ -86,7 +87,7 @@ public class Whisper {
         // swiftlint:disable line_length
         params.progress_callback = { (_: OpaquePointer?, _: OpaquePointer?, progress: Int32, userData: UnsafeMutableRawPointer?) in
         // swiftlint:enable line_length
-            guard let userData else { return }
+            guard let userData = userData else { return }
             let whisper = Unmanaged<Whisper>.fromOpaque(userData).takeUnretainedValue()
 
             DispatchQueue.main.async {
@@ -96,7 +97,7 @@ public class Whisper {
     }
 
     private func cleanupCallbacks() {
-        guard let unmanagedSelf else { return }
+        guard let unmanagedSelf = unmanagedSelf else { return }
 
         unmanagedSelf.release()
         self.unmanagedSelf = nil