diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index c6c64bcbfecbff897f11d6c727bb333d37082b2a..5171f43feff8db07c4f5ca2f0ac2f1562d5c98e0 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -9,7 +9,7 @@ slc6-gcc48:
     - mkdir build 
     - cd build
     - cmake -GNinja -D DD4HEP_USE_GEANT4=ON -D DD4HEP_USE_BOOST=ON -DBoost_NO_BOOST_CMAKE=ON -D DD4HEP_USE_LCIO=ON -D BUILD_TESTING=ON -DCLHEP_DIR=$CLHEP -D Geant4_DIR=$G4INSTALL/lib64/Geant4-10.1.3 -D DD4HEP_USE_CXX11=ON ..        
-    - ninja
+    - ninja -j6
     - ninja install
     - . ../bin/thisdd4hep.sh
     - ctest --output-on-failure
@@ -17,7 +17,7 @@ slc6-gcc48:
     - mkdir build
     - cd build
     - cmake -GNinja ..
-    - ninja
+    - ninja -j6
     - ninja install
     - ctest --output-on-failure
     - cd ../..
@@ -35,7 +35,7 @@ slc6-gcc49:
     - mkdir build 
     - cd build
     - cmake -GNinja -D DD4HEP_USE_GEANT4=ON -D DD4HEP_USE_BOOST=ON -DBoost_NO_BOOST_CMAKE=ON -D DD4HEP_USE_LCIO=ON -D BUILD_TESTING=ON -DCLHEP_DIR=$CLHEP -D Geant4_DIR=$G4INSTALL/lib64/Geant4-10.1.3 -D DD4HEP_USE_CXX11=ON ..        
-    - ninja
+    - ninja -j6
     - ninja install
     - . ../bin/thisdd4hep.sh
     - ctest --output-on-failure
@@ -43,7 +43,7 @@ slc6-gcc49:
     - mkdir build
     - cd build
     - cmake -GNinja ..
-    - ninja
+    - ninja -j6
     - ninja install
     - ctest --output-on-failure
     - cd ../..
@@ -61,7 +61,7 @@ centos7-gcc49:
     - mkdir build 
     - cd build
     - cmake -GNinja -D DD4HEP_USE_GEANT4=ON -D DD4HEP_USE_BOOST=ON -DBoost_NO_BOOST_CMAKE=ON -D DD4HEP_USE_LCIO=ON -D BUILD_TESTING=ON -DCLHEP_DIR=$CLHEP -D Geant4_DIR=$G4INSTALL/lib64/Geant4-10.1.3 -D DD4HEP_USE_CXX11=ON ..        
-    - ninja
+    - ninja -j6
     - ninja install
     - . ../bin/thisdd4hep.sh
     - ctest --output-on-failure
@@ -69,7 +69,7 @@ centos7-gcc49:
     - mkdir build
     - cd build
     - cmake -GNinja ..
-    - ninja
+    - ninja -j6
     - ninja install
     - ctest --output-on-failure
     - cd ../..