diff --git a/src/main/org/apache/tools/ant/types/defaults.properties b/src/main/org/apache/tools/ant/types/defaults.properties
index 0b24f6c30..e2570882b 100644
--- a/src/main/org/apache/tools/ant/types/defaults.properties
+++ b/src/main/org/apache/tools/ant/types/defaults.properties
@@ -19,3 +19,4 @@ selector=org.apache.tools.ant.types.selectors.SelectSelector
 zipfileset=org.apache.tools.ant.types.ZipFileSet
 scriptfilter=org.apache.tools.ant.types.optional.ScriptFilter
 propertyset=org.apache.tools.ant.types.PropertySet
+assertion=org.apache.tools.ant.types.Assertion
\ No newline at end of file