diff --git a/persistentGraph.ml b/persistentGraph.ml
index 0b8b99d0..8788a220 100644
--- a/persistentGraph.ml
+++ b/persistentGraph.ml
@@ -23,7 +23,7 @@ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *)
 
-(** {1 A simple mutable directed graph.} *)
+(** {1 A simple polymorphic directed graph.} *)
 
 type ('v, 'e) t = ('v, ('v, 'e) node) PHashtbl.t
   (** Graph parametrized by a type for vertices, and one for edges *)
diff --git a/persistentGraph.mli b/persistentGraph.mli
index 90cb0109..6ca542bb 100644
--- a/persistentGraph.mli
+++ b/persistentGraph.mli
@@ -23,7 +23,7 @@ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *)
 
-(** {1 A simple persistent directed graph.} *)
+(** {1 A simple polymorphic directed graph.} *)
 
 (** {2 Basics} *)