diff --git a/Packages/CandidateUI/Sources/CandidateUI/VerticalCandidateController.swift b/Packages/CandidateUI/Sources/CandidateUI/VerticalCandidateController.swift
index cdfe3a70..5f38a324 100644
--- a/Packages/CandidateUI/Sources/CandidateUI/VerticalCandidateController.swift
+++ b/Packages/CandidateUI/Sources/CandidateUI/VerticalCandidateController.swift
@@ -450,8 +450,8 @@ extension VerticalCandidateController: NSTableViewDataSource, NSTableViewDelegat
         }
 
         keyLabelStripView.keyLabelFont = keyLabelFont
-        let keyLabels = keyLabels[0..<Int(keyLabelCount)].map { $0.displayedText }
-        keyLabelStripView.keyLabels = keyLabels
+        let actualKeyLabels = keyLabels[0..<Int(keyLabelCount)].map { $0.displayedText }
+        keyLabelStripView.keyLabels = actualKeyLabels
         keyLabelStripView.labelOffsetY = (keyLabelFontSize >= candidateFontSize) ? 0.0 : floor((candidateFontSize - keyLabelFontSize) / 2.0)
 
         let rowHeight = ceil(fontSize * 1.25)
@@ -461,7 +461,7 @@ extension VerticalCandidateController: NSTableViewDataSource, NSTableViewDelegat
         let textAttr: [NSAttributedString.Key: AnyObject] = [.font: keyLabelFont]
         let boundingBox = NSSize(width: 1600.0, height: 1600.0)
 
-        for label in keyLabels {
+        for label in actualKeyLabels {
             let rect = (label as NSString).boundingRect(with: boundingBox, options: .usesLineFragmentOrigin, attributes: textAttr)
             maxKeyLabelWidth = max(rect.size.width, maxKeyLabelWidth)
         }
diff --git a/Source/InputMethodController.swift b/Source/InputMethodController.swift
index 98262b9c..c7d79b75 100644
--- a/Source/InputMethodController.swift
+++ b/Source/InputMethodController.swift
@@ -310,9 +310,9 @@ extension McBopomofoInputMethodController {
         // then we defer the update in the next runloop round -- so that the composing buffer is not
         // meaninglessly flushed, an annoying bug in Terminal.app since Mac OS X 10.5
         if (client as? IMKTextInput)?.bundleIdentifier() == "com.apple.Terminal" && NSStringFromClass(client.self as! AnyClass) != "IPMDServerClientWrapper" {
-            let currentDeferredClient = currentDeferredClient
+            let innerCurrentDeferredClient = currentDeferredClient
             DispatchQueue.main.asyncAfter(deadline: DispatchTime.now()) {
-                (currentDeferredClient as? IMKTextInput)?.insertText(buffer, replacementRange: NSRange(location: NSNotFound, length: NSNotFound))
+                (innerCurrentDeferredClient as? IMKTextInput)?.insertText(buffer, replacementRange: NSRange(location: NSNotFound, length: NSNotFound))
             }
         }
         (client as? IMKTextInput)?.insertText(buffer, replacementRange: NSRange(location: NSNotFound, length: NSNotFound))
diff --git a/Source/InputState.swift b/Source/InputState.swift
index 74476cd0..23f2f39c 100644
--- a/Source/InputState.swift
+++ b/Source/InputState.swift
@@ -247,8 +247,8 @@ class InputState: NSObject {
             let text = (composingBuffer as NSString).substring(with: markedRange)
             let (exactBegin, _) = (composingBuffer as NSString).characterIndex(from: markedRange.location)
             let (exactEnd, _) = (composingBuffer as NSString).characterIndex(from: markedRange.location + markedRange.length)
-            let readings = readings[exactBegin..<exactEnd]
-            let joined = readings.joined(separator: "-")
+            let selectedReadings = readings[exactBegin..<exactEnd]
+            let joined = selectedReadings.joined(separator: "-")
             return "\(text) \(joined)"
         }
     }
diff --git a/Source/main.swift b/Source/main.swift
index e871588a..00e01f03 100644
--- a/Source/main.swift
+++ b/Source/main.swift
@@ -30,9 +30,9 @@ private func install() -> Int32 {
         return -1
     }
     let bundleUrl = Bundle.main.bundleURL
-    var inputSource = InputSourceHelper.inputSource(for: bundleID)
+    var maybeInputSource = InputSourceHelper.inputSource(for: bundleID)
 
-    if inputSource == nil {
+    if maybeInputSource == nil {
         NSLog("Registering input source \(bundleID) at \(bundleUrl.absoluteString)");
         // then register
         let status = InputSourceHelper.registerTnputSource(at: bundleUrl)
@@ -42,10 +42,10 @@ private func install() -> Int32 {
             return -1
         }
 
-        inputSource = InputSourceHelper.inputSource(for: bundleID)
+        maybeInputSource = InputSourceHelper.inputSource(for: bundleID)
     }
 
-    guard let inputSource = inputSource else {
+    guard let inputSource = maybeInputSource else {
         NSLog("Fatal error: Cannot find input source \(bundleID) after registration.")
         return -1
     }