diff --git a/README.md b/README.md
index a0382ef..406541b 100644
--- a/README.md
+++ b/README.md
@@ -79,6 +79,7 @@ echo '{"a":1,"b":3}' | jq > 2.json
 ```
 
 ### `comm-x` <a id="comm-x"></a>
+`comm` essentially performs set intersection/difference; `comm-x` allows you to run a pipeline of commands on each input, before comparing them.
 
 #### Usage <a id="comm-x-usage"></a>
 <!-- `bmdf comm-x` -->
@@ -86,8 +87,8 @@ echo '{"a":1,"b":3}' | jq > 2.json
 comm-x
 # Usage: comm-x [OPTIONS] [exec_cmd...] <path1> <path2>
 #
-#   Compare (`comm`) two files after running them through a pipeline of other
-#   commands.
+#   Select or reject lines common to two input streams, after running each
+#   through a pipeline of other commands.
 #
 # Options:
 #   -1, --exclude-1              Exclude lines only found in the first pipeline
diff --git a/qmdx/comm_x/__init__.py b/qmdx/comm_x/__init__.py
index 5805ac8..3e04327 100644
--- a/qmdx/comm_x/__init__.py
+++ b/qmdx/comm_x/__init__.py
@@ -30,7 +30,7 @@ def main(
     exec_cmds: Tuple[str, ...],
     args: Tuple[str, ...],
 ):
-    """Compare (`comm`) two files after running them through a pipeline of other commands."""
+    """Select or reject lines common to two input streams, after running each through a pipeline of other commands."""
     if len(args) < 2:
         raise ValueError('Must provide at least two files to comm')
 
diff --git a/requirements-ci.txt b/requirements-ci.txt
index d64aa34..3cebf55 100644
--- a/requirements-ci.txt
+++ b/requirements-ci.txt
@@ -1 +1 @@
-bmdf>=0.3.6
+bmdf>=0.4.0
diff --git a/requirements.txt b/requirements.txt
index cff6469..66094e7 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,2 @@
 click
-utz>=0.12.2
+utz>=0.13.0