diff --git a/.travis.yml b/.travis.yml
index 21e82b2f962..6a1f90bd0b8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,7 +10,7 @@ addons:
       - gdb
       - python-dbg
       - python3-dbg
-      #- libzmq-dev  # previously needed by IPython/Tornado, now embedded in pyzmq
+      - libzmq-dev  # needed by IPython/Tornado
       #- gcc-8
       #- g++-8
 
diff --git a/test-requirements-cpython.txt b/test-requirements-cpython.txt
index 39e00d52702..51061ff7d41 100644
--- a/test-requirements-cpython.txt
+++ b/test-requirements-cpython.txt
@@ -1,4 +1,4 @@
 jupyter
 line_profiler
-# transitive dependency of jupyter (18.0.0 comes with a new libzmq)
-pyzmq>=18
+# transitive dependency of jupyter (18.0.0 is broken)
+pyzmq<18