diff --git a/YamlDotNet.Benchmark/Program.cs b/YamlDotNet.Benchmark/Program.cs
index 9fc2ebd9..00802d17 100644
--- a/YamlDotNet.Benchmark/Program.cs
+++ b/YamlDotNet.Benchmark/Program.cs
@@ -1,4 +1,11 @@
-using BenchmarkDotNet.Running;
-using YamlDotNet.Benchmark;
+using YamlDotNet.Serialization;
 
-BenchmarkSwitcher.FromAssembly(typeof(YamlStreamBenchmark).Assembly).Run(args);
+var serializer = new SerializerBuilder()
+    .WithQuotingNecessaryStrings()
+    .Build();
+
+var s = "\t, something";
+var yaml = serializer.Serialize(s);
+Console.WriteLine(yaml);
+var deserializer = new DeserializerBuilder().Build();
+var value = deserializer.Deserialize(yaml);
diff --git a/YamlDotNet.Test/Serialization/SerializationTests.cs b/YamlDotNet.Test/Serialization/SerializationTests.cs
index d46bc25e..a67c9ae5 100644
--- a/YamlDotNet.Test/Serialization/SerializationTests.cs
+++ b/YamlDotNet.Test/Serialization/SerializationTests.cs
@@ -2429,6 +2429,36 @@ public void SerializeEnumAsNumber()
             Assert.Equal(TestEnumAsNumber.Test1 | TestEnumAsNumber.Test2, v);
         }
 
+        [Fact]
+        public void TabsGetQuotedWhenQuoteNecessaryStringsIsOn()
+        {
+            var serializer = new SerializerBuilder()
+                .WithQuotingNecessaryStrings()
+                .Build();
+
+            var s = "\t, something";
+            var yaml = serializer.Serialize(s);
+            Console.WriteLine(yaml);
+            var deserializer = new DeserializerBuilder().Build();
+            var value = deserializer.Deserialize(yaml);
+            Assert.Equal(s, value);
+        }
+
+        [Fact]
+        public void SpacesGetQuotedWhenQuoteNecessaryStringsIsOn()
+        {
+            var serializer = new SerializerBuilder()
+                .WithQuotingNecessaryStrings()
+                .Build();
+
+            var s = " , something";
+            var yaml = serializer.Serialize(s);
+            Console.WriteLine(yaml);
+            var deserializer = new DeserializerBuilder().Build();
+            var value = deserializer.Deserialize(yaml);
+            Assert.Equal(s, value);
+        }
+
         [Flags]
         private enum TestEnumAsNumber
         {
diff --git a/YamlDotNet/Serialization/EventEmitters/TypeAssigningEventEmitter.cs b/YamlDotNet/Serialization/EventEmitters/TypeAssigningEventEmitter.cs
index e84b9b69..702907ff 100644
--- a/YamlDotNet/Serialization/EventEmitters/TypeAssigningEventEmitter.cs
+++ b/YamlDotNet/Serialization/EventEmitters/TypeAssigningEventEmitter.cs
@@ -45,6 +45,7 @@ public sealed class TypeAssigningEventEmitter : ChainedEventEmitter
                 + @"|[-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?" // float number
                 + @"|[-+]?(\.inf|\.Inf|\.INF)"
                 + @"|\.nan|\.NaN|\.NAN"
+                + @"|\s.*"
             + @")$";
 
         /// <summary>
diff --git a/tools/build/AutoNumberToStringConverter.cs b/tools/build/AutoNumberToStringConverter.cs
index 1d9cde74..1d406bba 100644
--- a/tools/build/AutoNumberToStringConverter.cs
+++ b/tools/build/AutoNumberToStringConverter.cs
@@ -29,7 +29,7 @@ public override string Read(ref Utf8JsonReader reader, Type typeToConvert, JsonS
 
             if (reader.TokenType == JsonTokenType.String)
             {
-                return reader.GetString();
+                return reader.GetString()!;
             }
 
             using var document = JsonDocument.ParseValue(ref reader);
diff --git a/tools/build/BuildDefinition.cs b/tools/build/BuildDefinition.cs
index ee056df0..415a4470 100644
--- a/tools/build/BuildDefinition.cs
+++ b/tools/build/BuildDefinition.cs
@@ -66,7 +66,7 @@ public static async Task<GitVersion> ResolveVersion(Options options, PreviousRel
                 };
                 jsonOptions.Converters.Add(new AutoNumberToStringConverter());
 
-                version = JsonSerializer.Deserialize<GitVersion>(versionJson, jsonOptions);
+                version = JsonSerializer.Deserialize<GitVersion>(versionJson, jsonOptions)!;
 
                 // Workaround to prevent issues with some consumers of the NuGet API that build
                 // links manually instead of following the links that come in the response.
@@ -290,7 +290,7 @@ public static async Task LinkPullRequestsToReleases(GitVersion version)
 
             var release = await releaseResponse.EnsureSuccessStatusCode().Content.ReadAsAsync<GitHubApiModels.Release>();
 
-            var linkedIssues = Regex.Matches(release.body, @"#(\d+)").Select(m => m.Groups[1].Value);
+            var linkedIssues = Regex.Matches(release.body ?? string.Empty, @"#(\d+)").Select(m => m.Groups[1].Value);
             WriteVerbose($"Found the following issues / pull requests: {string.Join(",", linkedIssues)}");
 
             foreach (var issueNumber in linkedIssues)
@@ -342,12 +342,12 @@ public static Task Document(Options options)
 
             const string ns = "http://microsoft.com/schemas/VisualStudio/TeamTest/2010";
 
-            var testDefinitions = report.Root
+            var testDefinitions = report.Root!
                 .Element(XName.Get("TestDefinitions", ns))!
                 .Elements(XName.Get("UnitTest", ns))
                 .Select(e =>
                 {
-                    var testMethod = e.Element(XName.Get("TestMethod", ns));
+                    var testMethod = e.Element(XName.Get("TestMethod", ns))!;
 
                     var sampleClassName = testMethod.Attribute("className")!.Value;
                     var sampleMethodName = testMethod.Attribute("name")!.Value;