diff --git a/packages/hxtorch/package.py b/packages/hxtorch/package.py
index b2a5ab2e48cfc3df07516ef841903b59ecefd349..f6579e3beb4dc003c43d36fc946210aaad4f7dc1 100644
--- a/packages/hxtorch/package.py
+++ b/packages/hxtorch/package.py
@@ -13,10 +13,10 @@ class Hxtorch(WafPackage):
     # This repo provides a waf binary used for the build below
     git      = "https://github.com/electronicvisions/pynn-brainscales.git"
 
-    version('4.0-a1', branch='waf')
+    version('4.0-a2', branch='waf')
 
     # PPU compiler dependencies
-    depends_on('oppulance@4.0:')
+    depends_on('oppulance@4.0-a2')
 
     # host software dependencies
     depends_on('bitsery', type=('build', 'link', 'run'))
@@ -137,8 +137,6 @@ class Hxtorch(WafPackage):
         """Setup and configure the project."""
 
         self.waf('setup', '--repo-db-url=https://github.com/electronicvisions/projects', '--without-munge',
-            '--without-sctrltp-python-bindings',
-            '--without-hxcomm-python-bindings',
             '--project=hxtorch@ebrains-' + str(spec.version),
             '--project=haldls@ebrains-' + str(spec.version),
             '--project=grenade@ebrains-' + str(spec.version),
diff --git a/packages/oppulance/package.py b/packages/oppulance/package.py
index eb4a89bc3f86824ef4913387468e19fc8488c567..418bd5344b3526cb4a96f844855a0e88df7e1378 100644
--- a/packages/oppulance/package.py
+++ b/packages/oppulance/package.py
@@ -21,8 +21,8 @@ class Oppulance(Package):
 
     releases = [
         {
-            'version': '4.0-a1',
-            'tag': 'ebrains-4.0-a1'
+            'version': '4.0-a2',
+            'tag': 'ebrains-4.0-a2'
         },
     ]
 
diff --git a/packages/pynn-brainscales/package.py b/packages/pynn-brainscales/package.py
index bc1d2e2dd842354964586e3ac9e1acba0e687bb2..020dfac2169f7737f59558d68d0db5f323e8be3b 100644
--- a/packages/pynn-brainscales/package.py
+++ b/packages/pynn-brainscales/package.py
@@ -11,10 +11,10 @@ class PynnBrainscales(WafPackage):
     homepage = "https://github.com/electronicvisions/pynn-brainscales"
     git      = "https://github.com/electronicvisions/pynn-brainscales.git"
 
-    version('4.0-a1', branch='waf')
+    version('4.0-a2', branch='waf')
 
     # PPU compiler dependencies
-    depends_on('oppulance@4.0:')
+    depends_on('oppulance@4.0-a2')
 
     # host software dependencies
     depends_on('bitsery', type=('build', 'link', 'run'))
@@ -103,8 +103,6 @@ class PynnBrainscales(WafPackage):
         """Setup and configure the project."""
 
         self.waf('setup', '--repo-db-url=https://github.com/electronicvisions/projects', '--without-munge',
-            '--without-sctrltp-python-bindings',
-            '--without-hxcomm-python-bindings',
             '--project=pynn-brainscales@ebrains-' + str(spec.version),
             '--project=haldls@ebrains-' + str(spec.version),
             '--project=grenade@ebrains-' + str(spec.version),
diff --git a/spack.yaml b/spack.yaml
index 01be085cd7e01c5538b80597fdbfb4542c1db78d..ac8b6f4387fdcc926319d1984382ef33276fd10e 100644
--- a/spack.yaml
+++ b/spack.yaml
@@ -30,6 +30,7 @@ spack:
     - py-pyaescrypt
     - py-formencode
     - tvb-framework ^binutils+ld+gold
+    - py-pybind11@2.10.1:
     - pynn-brainscales@4.0-a1 ^log4cxx@0.10.0 ^googletest@1.11.0:+gmock
     - hxtorch@4.0-a1 ^log4cxx@0.10.0 ^googletest@1.11.0:+gmock
     - py-neo