diff --git a/src/Markdig.Tests/Specs/JiraLinks.md b/src/Markdig.Tests/Specs/JiraLinks.md
index c66efc907..5088bc6b2 100644
--- a/src/Markdig.Tests/Specs/JiraLinks.md
+++ b/src/Markdig.Tests/Specs/JiraLinks.md
@@ -10,7 +10,7 @@ var pipeline = new MarkdownPipelineBuilder()
 
 The rules for detecting a link are:
 
-- The project key must be composed of one or more capitalized ASCII letter `[A-Z]+`
+- The project key must be composed of one or more capitalized ASCII letters or digits `[A-Z,0-9]+`
 - A single hyphen `-` must separate the project key and issue number.
 - The issue number is composed of 1 or more digits `[0, 9]+`
 - The reference must be preceded by either `(` or whitespace or EOF.
@@ -24,6 +24,18 @@ This is a ABCD-123 issue
 <p>This is a <a href="http://your.company.abc/browse/ABCD-123" target="blank">ABCD-123</a> issue</p>
 ````````````````````````````````
 
+```````````````````````````````` example
+This is a ABC4-123 issue
+.
+<p>This is a <a href="http://your.company.abc/browse/ABC4-123" target="blank">ABC4-123</a> issue</p>
+````````````````````````````````
+
+```````````````````````````````` example
+This is a ABC45-123 issue
+.
+<p>This is a <a href="http://your.company.abc/browse/ABC45-123" target="blank">ABC45-123</a> issue</p>
+````````````````````````````````
+
 ```````````````````````````````` example
 This is a KIRA-1 issue
 .
@@ -44,6 +56,12 @@ This is a (ABCD-123) issue
 <p>This is a (<a href="http://your.company.abc/browse/ABCD-123" target="blank">ABCD-123</a>) issue</p>
 ````````````````````````````````
 
+```````````````````````````````` example
+This is a (ABC4-123) issue
+.
+<p>This is a (<a href="http://your.company.abc/browse/ABC4-123" target="blank">ABC4-123</a>) issue</p>
+````````````````````````````````
+
 ```````````````````````````````` example
 This is a (KIRA-1) issue
 .
@@ -75,3 +93,9 @@ This is not JIRA- issue
 .
 <p>This is not JIRA- issue</p>
 ````````````````````````````````
+
+```````````````````````````````` example
+This is not JIR4- issue
+.
+<p>This is not JIR4- issue</p>
+````````````````````````````````