diff --git a/src/Slack.Webhooks.Tests/packages.config b/src/Slack.Webhooks.Tests/packages.config
index b5757f0..c4877fa 100644
--- a/src/Slack.Webhooks.Tests/packages.config
+++ b/src/Slack.Webhooks.Tests/packages.config
@@ -26,7 +26,7 @@
   <package id="System.Runtime.Numerics" version="4.3.0" targetFramework="net45" />
   <package id="System.Text.Encoding" version="4.3.0" targetFramework="net45" />
   <package id="System.Text.Encoding.Extensions" version="4.3.0" targetFramework="net45" />
-  <package id="System.Text.RegularExpressions" version="4.3.0" targetFramework="net45" />
+  <package id="System.Text.RegularExpressions" version="4.3.1" targetFramework="net45" />
   <package id="System.Threading" version="4.3.0" targetFramework="net45" />
   <package id="System.Threading.Tasks" version="4.3.0" targetFramework="net45" />
   <package id="System.Xml.ReaderWriter" version="4.3.0" targetFramework="net45" />