diff --git a/src/Microsoft.AspNet.Mvc.Core/Formatters/FormatterMappings.cs b/src/Microsoft.AspNet.Mvc.Core/Formatters/FormatterMappings.cs
index d72814bd51..e7b0b70ac5 100644
--- a/src/Microsoft.AspNet.Mvc.Core/Formatters/FormatterMappings.cs
+++ b/src/Microsoft.AspNet.Mvc.Core/Formatters/FormatterMappings.cs
@@ -90,7 +90,7 @@ namespace Microsoft.AspNet.Mvc.Formatters
                 throw new ArgumentException(Resources.ArgumentCannotBeNullOrEmpty, nameof(format));
             }
 
-            if (format.StartsWith("."))
+            if (format.StartsWith(".", StringComparison.Ordinal))
             {
                 if (format == ".")
                 {
diff --git a/src/Microsoft.AspNet.Mvc.Core/VirtualFileResult.cs b/src/Microsoft.AspNet.Mvc.Core/VirtualFileResult.cs
index 5dd5c302a5..96a708c257 100644
--- a/src/Microsoft.AspNet.Mvc.Core/VirtualFileResult.cs
+++ b/src/Microsoft.AspNet.Mvc.Core/VirtualFileResult.cs
@@ -97,7 +97,7 @@ namespace Microsoft.AspNet.Mvc
             var fileProvider = GetFileProvider(response.HttpContext.RequestServices);
 
             var normalizedPath = FileName;
-            if (normalizedPath.StartsWith("~"))
+            if (normalizedPath.StartsWith("~", StringComparison.Ordinal))
             {
                 normalizedPath = normalizedPath.Substring(1);
             }