diff --git a/libse/FixCasing.cs b/libse/FixCasing.cs
index 162abbcd9..749ac58dd 100644
--- a/libse/FixCasing.cs
+++ b/libse/FixCasing.cs
@@ -66,11 +66,12 @@ namespace Nikse.SubtitleEdit.Core
             }
         }
 
-        private static string FixEnglishAloneILowerToUpper(string text)
+        private static string FixEnglishAloneILowerToUpper(string input)
         {
             const string pre = " >¡¿♪♫([";
             const string post = " <!?.:;,♪♫)]";
 
+            var text = input;
             if (text.StartsWith("I-i ", StringComparison.Ordinal))
             {
                 text = text.Remove(0, 3).Insert(0, "I-I");
@@ -142,8 +143,9 @@ namespace Nikse.SubtitleEdit.Core
             return text;
         }
 
-        private string FixCasingAfterTitles(string text)
+        private string FixCasingAfterTitles(string input)
         {
+            var text = input;
             var titles = new[] { "Mrs.", "Miss.", "Mr.", "Ms.", "Dr." };
             var notChangeWords = new[] { "does", "has", "will", "is", "and", "for", "but", "or", "of" };
             for (int i = 0; i < text.Length - 4; i++)
@@ -171,9 +173,9 @@ namespace Nikse.SubtitleEdit.Core
             return text;
         }
 
-        private string Fix(string text, string lastLine, List<string> nameList, CultureInfo subtitleCulture, double millisecondsFromLast)
+        private string Fix(string original, string lastLine, List<string> nameList, CultureInfo subtitleCulture, double millisecondsFromLast)
         {
-            string original = text;
+            var text = original;
             if (FixNormal)
             {
                 if (FixNormalOnlyAllUppercase && text != text.ToUpper(subtitleCulture))
diff --git a/libse/Forms/FixCommonErrors/Helper.cs b/libse/Forms/FixCommonErrors/Helper.cs
index 4187db353..2801c7b9d 100644
--- a/libse/Forms/FixCommonErrors/Helper.cs
+++ b/libse/Forms/FixCommonErrors/Helper.cs
@@ -47,8 +47,9 @@ namespace Nikse.SubtitleEdit.Core.Forms.FixCommonErrors
             return letter;
         }
 
-        public static string FixEllipsesStartHelper(string text)
+        public static string FixEllipsesStartHelper(string input)
         {
+            var text = input;
             if (string.IsNullOrEmpty(text) || text.Trim().Length < 4 || !(text.Contains("..", StringComparison.Ordinal) || text.Contains(". .", StringComparison.Ordinal)))
             {
                 return text;
diff --git a/libse/Forms/RemoveTextForHI.cs b/libse/Forms/RemoveTextForHI.cs
index 31a5ae2e9..9e0c9fff6 100644
--- a/libse/Forms/RemoveTextForHI.cs
+++ b/libse/Forms/RemoveTextForHI.cs
@@ -8,8 +8,8 @@ namespace Nikse.SubtitleEdit.Core.Forms
     {
         public RemoveTextForHISettings Settings { get; set; }
 
-        public List<int> Warnings;
-        public int WarningIndex;
+        public List<int> Warnings { get; set; }
+        public int WarningIndex { get; set; }
 
         // interjection
         private readonly InterjectionRemoveContext _interjectionRemoveContext;
@@ -648,9 +648,9 @@ namespace Nikse.SubtitleEdit.Core.Forms
 
         private static readonly char[] TrimStartNoiseChar = { '-', ' ' };
 
-        public string RemoveTextFromHearImpaired(string text)
+        public string RemoveTextFromHearImpaired(string input)
         {
-            if (StartsAndEndsWithHearImpairedTags(HtmlUtil.RemoveHtmlTags(text, true).TrimStart(TrimStartNoiseChar)))
+            if (StartsAndEndsWithHearImpairedTags(HtmlUtil.RemoveHtmlTags(input, true).TrimStart(TrimStartNoiseChar)))
             {
                 return string.Empty;
             }
@@ -659,15 +659,14 @@ namespace Nikse.SubtitleEdit.Core.Forms
             {
                 foreach (var removeIfTextContain in Settings.RemoveIfTextContains)
                 {
-                    if (text.Contains(removeIfTextContain))
+                    if (input.Contains(removeIfTextContain))
                     {
                         return string.Empty;
                     }
                 }
             }
 
-            string oldText = text;
-            text = RemoveColon(text);
+            var text = RemoveColon(input);
             string pre = " >-\"'‘`´♪¿¡.…—";
             string post = " -\"'`´♪.!?:…—";
             if (Settings.RemoveTextBetweenCustomTags)
@@ -852,12 +851,12 @@ namespace Nikse.SubtitleEdit.Core.Forms
                 text = st.Pre + text + st.Post;
             }
 
-            if (oldText.TrimStart().StartsWith("- ", StringComparison.Ordinal) &&
+            if (input.TrimStart().StartsWith("- ", StringComparison.Ordinal) &&
                 text != null && !text.Contains(Environment.NewLine) &&
-                (oldText.Contains(Environment.NewLine + "- ") ||
-                 oldText.Contains(Environment.NewLine + " - ") ||
-                 oldText.Contains(Environment.NewLine + "<i>- ") ||
-                 oldText.Contains(Environment.NewLine + "<i> - ")))
+                (input.Contains(Environment.NewLine + "- ") ||
+                 input.Contains(Environment.NewLine + " - ") ||
+                 input.Contains(Environment.NewLine + "<i>- ") ||
+                 input.Contains(Environment.NewLine + "<i> - ")))
             {
                 if (text.StartsWith("<i>-", StringComparison.Ordinal))
                 {
@@ -868,35 +867,35 @@ namespace Nikse.SubtitleEdit.Core.Forms
                     text = text.TrimStart().TrimStart('-').TrimStart();
                 }
             }
-            if (oldText.TrimStart().StartsWith('-') && !oldText.TrimStart().StartsWith("--", StringComparison.Ordinal) &&
+            if (input.TrimStart().StartsWith('-') && !input.TrimStart().StartsWith("--", StringComparison.Ordinal) &&
                 text != null && !text.Contains(Environment.NewLine) &&
-                (oldText.Contains(Environment.NewLine + "-") && !oldText.Contains(Environment.NewLine + "--") ||
-                 oldText.Contains(Environment.NewLine + " - ") ||
-                 oldText.Contains(Environment.NewLine + "<i>- ") ||
-                 oldText.Contains(Environment.NewLine + "<i> - ")))
+                (input.Contains(Environment.NewLine + "-") && !input.Contains(Environment.NewLine + "--") ||
+                 input.Contains(Environment.NewLine + " - ") ||
+                 input.Contains(Environment.NewLine + "<i>- ") ||
+                 input.Contains(Environment.NewLine + "<i> - ")))
             {
                 text = text.TrimStart().TrimStart('-').TrimStart();
             }
 
-            if (oldText.TrimStart().StartsWith("<i>- ", StringComparison.Ordinal) &&
+            if (input.TrimStart().StartsWith("<i>- ", StringComparison.Ordinal) &&
                 text != null && text.StartsWith("<i>- ", StringComparison.Ordinal) && !text.Contains(Environment.NewLine) &&
-                (oldText.Contains(Environment.NewLine + "- ") ||
-                 oldText.Contains(Environment.NewLine + " - ") ||
-                 oldText.Contains(Environment.NewLine + "<i>- ") ||
-                 oldText.Contains(Environment.NewLine + "<i> - ")))
+                (input.Contains(Environment.NewLine + "- ") ||
+                 input.Contains(Environment.NewLine + " - ") ||
+                 input.Contains(Environment.NewLine + "<i>- ") ||
+                 input.Contains(Environment.NewLine + "<i> - ")))
             {
                 text = text.Remove(3, 2);
             }
 
             if (text != null && !text.Contains(Environment.NewLine) &&
-                (oldText.Contains(':') && !text.Contains(':') ||
-                 oldText.Contains('[') && !text.Contains('[') ||
-                 oldText.Contains('(') && !text.Contains('(') ||
-                 oldText.Contains('{') && !text.Contains('{')) &&
-                (oldText.Contains(Environment.NewLine + "- ") ||
-                 oldText.Contains(Environment.NewLine + " - ") ||
-                 oldText.Contains(Environment.NewLine + "<i>- ") ||
-                 oldText.Contains(Environment.NewLine + "<i> - ")))
+                (input.Contains(':') && !text.Contains(':') ||
+                 input.Contains('[') && !text.Contains('[') ||
+                 input.Contains('(') && !text.Contains('(') ||
+                 input.Contains('{') && !text.Contains('{')) &&
+                (input.Contains(Environment.NewLine + "- ") ||
+                 input.Contains(Environment.NewLine + " - ") ||
+                 input.Contains(Environment.NewLine + "<i>- ") ||
+                 input.Contains(Environment.NewLine + "<i> - ")))
             {
                 text = text.TrimStart().TrimStart('-').TrimStart();
             }
@@ -925,7 +924,7 @@ namespace Nikse.SubtitleEdit.Core.Forms
                 text = "<i>" + text.Remove(0, removeText.Length).TrimStart(' ');
             }
 
-            if (oldText != text)
+            if (input != text)
             {
                 // insert spaces before "-"
                 text = text.Replace(Environment.NewLine + "- <i>", Environment.NewLine + "<i>- ");
diff --git a/libse/NoBreakAfterItem.cs b/libse/NoBreakAfterItem.cs
index 52e38d4f2..b3faed5aa 100644
--- a/libse/NoBreakAfterItem.cs
+++ b/libse/NoBreakAfterItem.cs
@@ -5,7 +5,7 @@ namespace Nikse.SubtitleEdit.Core
 {
     public class NoBreakAfterItem : IComparable<NoBreakAfterItem>
     {
-        public readonly Regex Regex;
+        public Regex Regex { get; }
         public readonly string Text;
 
         public NoBreakAfterItem(Regex regex, string text)
diff --git a/libse/SpellCheck/SpellCheckWordLists.cs b/libse/SpellCheck/SpellCheckWordLists.cs
index 8aca3a80a..8a677efa3 100644
--- a/libse/SpellCheck/SpellCheckWordLists.cs
+++ b/libse/SpellCheck/SpellCheckWordLists.cs
@@ -400,7 +400,7 @@ namespace Nikse.SubtitleEdit.Core.SpellCheck
                             if (startOk && endOk)
                             {
                                 i++;
-                                string id = string.Format("_@{0}_", i);
+                                string id = $"_@{i}_";
                                 replaceIds.Add(id);
                                 replaceNames.Add(wordWithDashesOrPeriods);
                                 text = text.Remove(indexStart, wordWithDashesOrPeriods.Length).Insert(indexStart, id);
diff --git a/libse/SubtitleFormats/Idx.cs b/libse/SubtitleFormats/Idx.cs
index efb93e8c1..d8e64584c 100644
--- a/libse/SubtitleFormats/Idx.cs
+++ b/libse/SubtitleFormats/Idx.cs
@@ -12,7 +12,7 @@ namespace Nikse.SubtitleEdit.Core.SubtitleFormats
         // timestamp: 00:00:01:401, filepos: 000000000
         private static readonly Regex RegexTimeCodes = new Regex(@"^timestamp: \d+:\d+:\d+:\d+, filepos: [\dabcdefABCDEF]+$", RegexOptions.Compiled);
 
-        public Hashtable NonTimeCodes = new Hashtable();
+        private readonly Hashtable _nonTimeCodes = new Hashtable();
 
         public override string Extension => ".idx";
 
@@ -41,9 +41,12 @@ namespace Nikse.SubtitleEdit.Core.SubtitleFormats
             const string paragraphWriteFormat = "timestamp: {0}, filepos: {1}";
 
             var tempNonTimeCodes = new Hashtable();
-            foreach (DictionaryEntry de in (subtitle.OriginalFormat as Idx).NonTimeCodes)
+            if (subtitle.OriginalFormat != null)
             {
-                tempNonTimeCodes.Add(de.Key, de.Value);
+                foreach (DictionaryEntry de in ((Idx)subtitle.OriginalFormat)._nonTimeCodes)
+                {
+                    tempNonTimeCodes.Add(de.Key, de.Value);
+                }
             }
 
             var sb = new StringBuilder();
@@ -96,20 +99,19 @@ namespace Nikse.SubtitleEdit.Core.SubtitleFormats
                 }
                 else
                 {
-                    int place;
                     if (subtitle.Paragraphs.Count == 0 ||
-                        !int.TryParse(subtitle.Paragraphs[subtitle.Paragraphs.Count - 1].Text, out place))
+                        !int.TryParse(subtitle.Paragraphs[subtitle.Paragraphs.Count - 1].Text, out var place))
                     {
                         place = -1;
                     }
 
-                    if (NonTimeCodes.ContainsKey(place))
+                    if (_nonTimeCodes.ContainsKey(place))
                     {
-                        NonTimeCodes[place] += Environment.NewLine + line;
+                        _nonTimeCodes[place] += Environment.NewLine + line;
                     }
                     else
                     {
-                        NonTimeCodes.Add(place, line);
+                        _nonTimeCodes.Add(place, line);
                     }
                 }
             }
@@ -120,14 +122,10 @@ namespace Nikse.SubtitleEdit.Core.SubtitleFormats
             // timestamp: 00:00:01:401, filepos: 000000000
             if (parts.Length == 7)
             {
-                int hours;
-                int minutes;
-                int seconds;
-                int milliseconds;
-                if (int.TryParse(parts[1], out hours) &&
-                    int.TryParse(parts[2], out minutes) &&
-                    int.TryParse(parts[3], out seconds) &&
-                    int.TryParse(parts[4], out milliseconds))
+                if (int.TryParse(parts[1], out var hours) &&
+                    int.TryParse(parts[2], out var minutes) &&
+                    int.TryParse(parts[3], out var seconds) &&
+                    int.TryParse(parts[4], out var milliseconds))
                 {
                     return new Paragraph
                     {
diff --git a/libse/SubtitleFormats/NciTimedRollUpCaptions.cs b/libse/SubtitleFormats/NciTimedRollUpCaptions.cs
index 40bc1d49a..8a9320e80 100644
--- a/libse/SubtitleFormats/NciTimedRollUpCaptions.cs
+++ b/libse/SubtitleFormats/NciTimedRollUpCaptions.cs
@@ -129,9 +129,9 @@ namespace Nikse.SubtitleEdit.Core.SubtitleFormats
             subtitle.Renumber();
         }
 
-        private static string FixText(string text)
+        private static string FixText(string input)
         {
-            text = text.Replace("\u0011P", Environment.NewLine);
+            var text = input.Replace("\u0011P", Environment.NewLine);
             text = text.Replace("\u00117", "♪");
 
             text = text.Replace("\u0012\u0029", string.Empty);
diff --git a/libse/SubtitleFormats/Spruce.cs b/libse/SubtitleFormats/Spruce.cs
index 565ce57c1..508e6e554 100644
--- a/libse/SubtitleFormats/Spruce.cs
+++ b/libse/SubtitleFormats/Spruce.cs
@@ -70,9 +70,9 @@ $ColorIndex4    = 3
             return sb.ToString();
         }
 
-        private static string EncodeText(string text)
+        private static string EncodeText(string input)
         {
-            text = HtmlUtil.FixUpperTags(text);
+            var text = HtmlUtil.FixUpperTags(input);
             bool allItalic = text.StartsWith("<i>", StringComparison.Ordinal) && text.EndsWith("</i>", StringComparison.Ordinal) && Utilities.CountTagInText(text, "<i>") == 1;
             text = text.Replace("<b>", Bold);
             text = text.Replace("</b>", Bold);
diff --git a/src/Forms/DurationsBridgeGaps.cs b/src/Forms/DurationsBridgeGaps.cs
index 592942a40..0b1620f97 100644
--- a/src/Forms/DurationsBridgeGaps.cs
+++ b/src/Forms/DurationsBridgeGaps.cs
@@ -22,11 +22,7 @@ namespace Nikse.SubtitleEdit.Forms
             set => numericUpDownMinMsBetweenLines.Value = value;
         }
 
-        public bool PreviousSubtitleTakesAllTime
-        {
-            get => radioButtonProlongEndTime.Checked;
-            set => radioButtonProlongEndTime.Checked = value;
-        }
+        public bool PreviousSubtitleTakesAllTime => radioButtonProlongEndTime.Checked;
 
         public DurationsBridgeGaps(Subtitle subtitle)
         {
diff --git a/src/UpdateResourceScript/Program.cs b/src/UpdateResourceScript/Program.cs
index 0d75d0ce3..b02767474 100644
--- a/src/UpdateResourceScript/Program.cs
+++ b/src/UpdateResourceScript/Program.cs
@@ -24,10 +24,10 @@ namespace UpdateResourceScript
     {
         private class VersionInfoResource
         {
-            public string StringFileInfo { get; private set; }
-            public string ProductVersion { get; private set; }
-            public string FileVersion { get; private set; }
-            public string FileFlags { get; private set; }
+            public string StringFileInfo { get; }
+            public string ProductVersion { get; }
+            public string FileVersion { get; }
+            public string FileFlags { get; }
 
             public VersionInfoResource(string assemblyFileName)
             {
@@ -77,13 +77,6 @@ namespace UpdateResourceScript
 
         private const string WorkInProgress = "Updating win32 resource script...";
 
-        private static void WriteWarning(string message)
-        {
-            Console.WriteLine();
-            Console.WriteLine("WARNING: " + message);
-            Console.Write(WorkInProgress);
-        }
-
         private static int Main(string[] args)
         {
             var myName = Environment.GetCommandLineArgs()[0];