diff --git a/containers/jug/Dockerfile.dev b/containers/jug/Dockerfile.dev
index 582ad65c1cb6d0b2ba228f8f68de5f7f2deef2af..af3a78712149670c53de9c1424faa91637d36472 100644
--- a/containers/jug/Dockerfile.dev
+++ b/containers/jug/Dockerfile.dev
@@ -157,7 +157,7 @@ RUN cd /opt/spack-environment                                           \
  && pip install --trusted-host pypi.org                                 \
                 --trusted-host files.pythonhosted.org                   \
                 --no-cache-dir                                          \
-        ipython matplotlib scipy yapf pandas                            \
+        ipython matplotlib scipy yapf pandas pycairo pyyaml             \
         jupyter jupyterlab uproot pyunfold seaborn                      \
  && echo -n ""                                                          \
  && echo "Executing cmake patch for dd4hep 16.1"                        \                
diff --git a/spack.yaml b/spack.yaml
index cc2d58a37b9ff696e0d8cde63e89465f97a80c8a..2acd16acf17f91a2f6956d86a21e133db71a9bab 100644
--- a/spack.yaml
+++ b/spack.yaml
@@ -9,9 +9,9 @@ spack:
     - clhep@2.4.4.0 cxxstd=17
     - eigen@3.3.9
     - python@3.7.8
-    - py-pip
-    - py-numpy
-    - py-pyyaml
+    - py-numpy@1.20.1
+    - py-pip@20.2
+    - pkg-config@0.29.2
     - xrootd@5.1.0 cxxstd=17 +python
     - root@6.22.08 cxxstd=17 
           +fftw +fortran +gdml +http +mlp +pythia8 
@@ -20,7 +20,7 @@ spack:
     - pythia8@8303
     - hepmc3@3.2.2 +python +rootio 
     - stow@2.3.1
-    - cairo+fc+ft+X+pdf+gobject
+    - cairo@1.16.0 +fc+ft+X+pdf+gobject
     - podio@0.13
     - geant4@10.7.1 cxxstd=17 +opengl +vecgeom +x11 +qt ^qt +opengl
     - dd4hep@1.16.1 +geant4 +assimp +hepmc3 +ipo
@@ -28,6 +28,6 @@ spack:
     - gaudi@34.0
     - dawn@3_91a
     - dawncut@1_54a
-    - opencascade
+    - opencascade@7.4.0p1
   concretization: together
   view: /usr/local