diff --git a/src/muz/rel/dl_base.h b/src/muz/rel/dl_base.h
index c14977c04..268cc602e 100644
--- a/src/muz/rel/dl_base.h
+++ b/src/muz/rel/dl_base.h
@@ -88,7 +88,7 @@ namespace datalog {
         typedef typename Traits::signature signature; //this must be a vector-like type
 
         /**
-           The client submits an initial class to be used as a base for signature. Then we excend it by
+           The client submits an initial class to be used as a base for signature. Then we extend it by
            the common signature methods into a signature_base class which then the client inherits from
            to obtain the actual signature class.
         */