diff --git a/src/Diagnostics/Roslyn/Core/ApiDesign/DeclarePublicAPIAnalyzer.cs b/src/Diagnostics/Roslyn/Core/ApiDesign/DeclarePublicAPIAnalyzer.cs
index c1b032d4f8261e91e9071bfd293f6106f1fa6da5..24aaa18b103f6b98d41263f3047b18f6da421b08 100644
--- a/src/Diagnostics/Roslyn/Core/ApiDesign/DeclarePublicAPIAnalyzer.cs
+++ b/src/Diagnostics/Roslyn/Core/ApiDesign/DeclarePublicAPIAnalyzer.cs
@@ -5,6 +5,7 @@
 using System.Collections.Immutable;
 using System.IO;
 using System.Linq;
+using System.Threading;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Text;
@@ -82,7 +83,7 @@ public override void Initialize(AnalysisContext context)
         {
             context.RegisterCompilationStartAction(compilationContext =>
             {
-                AdditionalText publicApiAdditionalText = TryGetPublicApiSpec(compilationContext.Options.AdditionalFiles);
+                AdditionalText publicApiAdditionalText = TryGetPublicApiSpec(compilationContext.Options.AdditionalFiles, compilationContext.CancellationToken);
                 var publicApiSourceText = publicApiAdditionalText.GetText(compilationContext.CancellationToken);
 
                 if (publicApiAdditionalText == null)
@@ -90,7 +91,7 @@ public override void Initialize(AnalysisContext context)
                     return;
                 }
 
-                HashSet<string> declaredPublicSymbols = ReadPublicSymbols(publicApiSourceText);
+                HashSet<string> declaredPublicSymbols = ReadPublicSymbols(publicApiSourceText, compilationContext.CancellationToken);
                 HashSet<string> examinedPublicTypes = new HashSet<string>();
                 object lockObj = new object();
 
@@ -203,12 +204,14 @@ internal static string GetPublicApiName(ISymbol symbol)
             return null;
         }
 
-        private static HashSet<string> ReadPublicSymbols(SourceText file)
+        private static HashSet<string> ReadPublicSymbols(SourceText file, CancellationToken cancellationToken)
         {
             HashSet<string> publicSymbols = new HashSet<string>();
 
             foreach (var line in file.Lines)
             {
+                cancellationToken.ThrowIfCancellationRequested();
+
                 var text = line.ToString();
 
                 if (!string.IsNullOrWhiteSpace(text))
@@ -248,10 +251,12 @@ private static bool IsPublicOrPublicProtected(ISymbol symbol)
             return false;
         }
 
-        private static AdditionalText TryGetPublicApiSpec(ImmutableArray<AdditionalText> additionalTexts)
+        private static AdditionalText TryGetPublicApiSpec(ImmutableArray<AdditionalText> additionalTexts, CancellationToken cancellationToken)
         {
             foreach (var text in additionalTexts)
             {
+                cancellationToken.ThrowIfCancellationRequested();
+
                 if (Path.GetFileName(text.Path).Equals(PublicApiFileName, StringComparison.OrdinalIgnoreCase))
                 {
                     return text;