diff --git a/src/main/org/apache/ant/antunit/antlib.xml b/src/main/org/apache/ant/antunit/antlib.xml
index 30c84a7..fca2bbd 100644
--- a/src/main/org/apache/ant/antunit/antlib.xml
+++ b/src/main/org/apache/ant/antunit/antlib.xml
@@ -243,7 +243,7 @@
   <macrodef name="assertMatches" backtrace="false">
     <attribute name="string"/>
     <attribute name="pattern"/>
-    <attribute name="casesensitive" default="false"/>
+    <attribute name="casesensitive" default="true"/>
     <attribute name="singleline" default="false"/>
     <attribute name="multiline" default="false"/>
     <attribute name="message"