diff --git a/package.xml b/package.xml
index e87def2..176dd14 100644
--- a/package.xml
+++ b/package.xml
@@ -18,8 +18,7 @@
 
   <author email="wieser@mit.edu">Eric Wieser</author>
 
-  <exec_depend condition="$ROS_PYTHON_VERSION == 2">python-numpy</exec_depend>
-  <exec_depend condition="$ROS_PYTHON_VERSION == 3">python3-numpy</exec_depend>
+  <exec_depend>python3-numpy</exec_depend>
   <exec_depend>rospy</exec_depend>
   <exec_depend>sensor_msgs</exec_depend>
   <exec_depend>nav_msgs</exec_depend>
diff --git a/src/ros_numpy/registry.py b/src/ros_numpy/registry.py
index 5442b93..2483293 100644
--- a/src/ros_numpy/registry.py
+++ b/src/ros_numpy/registry.py
@@ -27,7 +27,7 @@ def numpify(msg, *args, **kwargs):
 		return
 
 	conv = _to_numpy.get((msg.__class__, False))
-	if not conv and isinstance(msg, collections.Sequence):
+	if not conv and isinstance(msg, collections.abc.Sequence):
 		if not msg:
 			raise ValueError("Cannot determine the type of an empty Collection")
 		conv = _to_numpy.get((msg[0].__class__, True))