diff --git a/pkgs/development/libraries/openmpi/default.nix b/pkgs/development/libraries/openmpi/default.nix
index a279fe79940..b5651e8f02a 100644
--- a/pkgs/development/libraries/openmpi/default.nix
+++ b/pkgs/development/libraries/openmpi/default.nix
@@ -10,14 +10,14 @@
 
 let
   majorVersion = "3.1";
-  minorVersion = "0";
+  minorVersion = "2";
 
 in stdenv.mkDerivation rec {
   name = "openmpi-${majorVersion}.${minorVersion}";
 
   src = fetchurl {
     url = "http://www.open-mpi.org/software/ompi/v${majorVersion}/downloads/${name}.tar.bz2";
-    sha256 = "0v7hrmf1z5d1rmm0z5gi79l536j3z5s5b0kf9q5rr1fc4i0h8p5j";
+    sha256 = "1ibniapqki763agpfh65y284las083fqmj8m5b2pi8ilgy2fsm66";
   };
 
   postPatch = ''
diff --git a/pkgs/development/python-modules/mpi4py/default.nix b/pkgs/development/python-modules/mpi4py/default.nix
index 1b4ad50c781..6b69df61413 100644
--- a/pkgs/development/python-modules/mpi4py/default.nix
+++ b/pkgs/development/python-modules/mpi4py/default.nix
@@ -37,6 +37,8 @@ buildPythonPackage rec {
     # Needed to run the tests reliably. See:
     # https://bitbucket.org/mpi4py/mpi4py/issues/87/multiple-test-errors-with-openmpi-30
     export OMPI_MCA_rmaps_base_oversubscribe=yes
+    export OMPI_MCA_osc=sm
+    export OMPI_MCA_btl=self,vader
   '';
 
   setupPyBuildFlags = ["--mpicc=${mpi}/bin/mpicc"];