diff --git a/pom.xml b/pom.xml
index f83f8db..c1ae525 100644
--- a/pom.xml
+++ b/pom.xml
@@ -89,7 +89,7 @@
       <dependency>
         <groupId>com.io7m.jaffirm</groupId>
         <artifactId>com.io7m.jaffirm.core</artifactId>
-        <version>4.0.0</version>
+        <version>4.0.1</version>
       </dependency>
       <dependency>
         <groupId>com.io7m.junreachable</groupId>