diff --git a/base-10/opts.clang b/base-10/opts.clang
index 748ab4bb7f185b2b3e428be8ab59ca4c7deca8e5..faaba7d146743664fffe712a79738bab3c9ff060 100644
--- a/base-10/opts.clang
+++ b/base-10/opts.clang
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_COMPILER=/usr/bin/clang++-4.0 -DCMAKE_C_COMPILER=/usr/bin/clang-4.0 -DCXX_MAX_STANDARD=17 -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fcolor-diagnostics -ftemplate-backtrace-limit=0'"
+CMAKE_FLAGS="-DCMAKE_CXX_COMPILER=/usr/bin/clang++-4.0 -DCMAKE_C_COMPILER=/usr/bin/clang-4.0 -DCXX_MAX_STANDARD=17 -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fcolor-diagnostics -ftemplate-backtrace-limit=0' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-10/opts.gcc b/base-10/opts.gcc
index 466c3b9c93cef39a6cc5245f29a4be652e8bdad7..0fc48e1d04cc12ae5b0c1735c186c0b6211875a9 100644
--- a/base-10/opts.gcc
+++ b/base-10/opts.gcc
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_COMPILER=/usr/bin/g++ -DCMAKE_C_COMPILER=/usr/bin/gcc -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fdiagnostics-color=always'"
+CMAKE_FLAGS="-DCMAKE_CXX_COMPILER=/usr/bin/g++ -DCMAKE_C_COMPILER=/usr/bin/gcc -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fdiagnostics-color=always' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-10/opts.gcc.c++17 b/base-10/opts.gcc.c++17
index ab8d1dcab14a8be427183f01975cf26d871b9c04..188c7213946ec8b43ab0fc5783d16741e4c1918a 100644
--- a/base-10/opts.gcc.c++17
+++ b/base-10/opts.gcc.c++17
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_COMPILER=/usr/bin/g++-7 -DCMAKE_C_COMPILER=/usr/bin/gcc-7 -DCXX_MAX_STANDARD=17 -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fdiagnostics-color=always'"
+CMAKE_FLAGS="-DCMAKE_CXX_COMPILER=/usr/bin/g++-7 -DCMAKE_C_COMPILER=/usr/bin/gcc-7 -DCXX_MAX_STANDARD=17 -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fdiagnostics-color=always' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-16.04/opts.clang b/base-16.04/opts.clang
index 3746e5f682d066259f21eca531740c8bd126c3e4..8022ec1023c874950bb03c6ddc070d41f81dc4e3 100644
--- a/base-16.04/opts.clang
+++ b/base-16.04/opts.clang
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_COMPILER='/usr/bin/clang++' -DCMAKE_C_COMPILER=/usr/bin/clang -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fcolor-diagnostics -ftemplate-backtrace-limit=0'"
+CMAKE_FLAGS="-DCMAKE_CXX_COMPILER='/usr/bin/clang++' -DCMAKE_C_COMPILER=/usr/bin/clang -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fcolor-diagnostics -ftemplate-backtrace-limit=0' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-16.04/opts.gcc b/base-16.04/opts.gcc
index c8c75617b82639460a01538a40120755381e3382..7821ee3f217020ed899359f7c692766ef5b8c225 100644
--- a/base-16.04/opts.gcc
+++ b/base-16.04/opts.gcc
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_FLAGS='-O2 -g -Wall -fdiagnostics-color=always'"
+CMAKE_FLAGS="-DCMAKE_CXX_FLAGS='-O2 -g -Wall -fdiagnostics-color=always' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-16.10/opts.clang b/base-16.10/opts.clang
index 3746e5f682d066259f21eca531740c8bd126c3e4..8022ec1023c874950bb03c6ddc070d41f81dc4e3 100644
--- a/base-16.10/opts.clang
+++ b/base-16.10/opts.clang
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_COMPILER='/usr/bin/clang++' -DCMAKE_C_COMPILER=/usr/bin/clang -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fcolor-diagnostics -ftemplate-backtrace-limit=0'"
+CMAKE_FLAGS="-DCMAKE_CXX_COMPILER='/usr/bin/clang++' -DCMAKE_C_COMPILER=/usr/bin/clang -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fcolor-diagnostics -ftemplate-backtrace-limit=0' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-16.10/opts.gcc b/base-16.10/opts.gcc
index c8c75617b82639460a01538a40120755381e3382..7821ee3f217020ed899359f7c692766ef5b8c225 100644
--- a/base-16.10/opts.gcc
+++ b/base-16.10/opts.gcc
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_FLAGS='-O2 -g -Wall -fdiagnostics-color=always'"
+CMAKE_FLAGS="-DCMAKE_CXX_FLAGS='-O2 -g -Wall -fdiagnostics-color=always' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-8-backports/opts.clang b/base-8-backports/opts.clang
index e085c1901fb28db4ff846daf79eb4a03ac9cdc04..00b7e83b9e34d78982c4c54ba900c9a46a50d4e9 100644
--- a/base-8-backports/opts.clang
+++ b/base-8-backports/opts.clang
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_COMPILER='/usr/bin/clang++-3.8' -DCMAKE_C_COMPILER=/usr/bin/clang-3.8 -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fcolor-diagnostics -ftemplate-backtrace-limit=0'"
+CMAKE_FLAGS="-DCMAKE_CXX_COMPILER='/usr/bin/clang++-3.8' -DCMAKE_C_COMPILER=/usr/bin/clang-3.8 -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fcolor-diagnostics -ftemplate-backtrace-limit=0' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-8/opts.clang b/base-8/opts.clang
index d38c606eb2c6c365e5dda0c813504e28fa8de8b1..30a2c70e747348c417b6edf50d82823cab9c67d9 100644
--- a/base-8/opts.clang
+++ b/base-8/opts.clang
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_COMPILER='/usr/bin/clang++' -DCMAKE_C_COMPILER=/usr/bin/clang -DCMAKE_CXX_FLAGS='-O2 -Wall -ftemplate-backtrace-limit=0'"
+CMAKE_FLAGS="-DCMAKE_CXX_COMPILER='/usr/bin/clang++' -DCMAKE_C_COMPILER=/usr/bin/clang -DCMAKE_CXX_FLAGS='-O2 -Wall -ftemplate-backtrace-limit=0' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-8/opts.gcc b/base-8/opts.gcc
index 90868a568709c1442b21922d03d38270ed601ec7..2e5fea6f28fa045a02af5e91742d261a564ee9f3 100644
--- a/base-8/opts.gcc
+++ b/base-8/opts.gcc
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_FLAGS='-O2 -g -Wall'"
+CMAKE_FLAGS="-DCMAKE_CXX_FLAGS='-O2 -g -Wall' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-9/opts.clang b/base-9/opts.clang
index 3746e5f682d066259f21eca531740c8bd126c3e4..8022ec1023c874950bb03c6ddc070d41f81dc4e3 100644
--- a/base-9/opts.clang
+++ b/base-9/opts.clang
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_COMPILER='/usr/bin/clang++' -DCMAKE_C_COMPILER=/usr/bin/clang -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fcolor-diagnostics -ftemplate-backtrace-limit=0'"
+CMAKE_FLAGS="-DCMAKE_CXX_COMPILER='/usr/bin/clang++' -DCMAKE_C_COMPILER=/usr/bin/clang -DCMAKE_CXX_FLAGS='-O2 -g -Wall -fcolor-diagnostics -ftemplate-backtrace-limit=0' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"
diff --git a/base-9/opts.gcc b/base-9/opts.gcc
index c8c75617b82639460a01538a40120755381e3382..7821ee3f217020ed899359f7c692766ef5b8c225 100644
--- a/base-9/opts.gcc
+++ b/base-9/opts.gcc
@@ -1 +1 @@
-CMAKE_FLAGS="-DCMAKE_CXX_FLAGS='-O2 -g -Wall -fdiagnostics-color=always'"
+CMAKE_FLAGS="-DCMAKE_CXX_FLAGS='-O2 -g -Wall -fdiagnostics-color=always' ${DUNECI_PARALLEL:+-DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL}}"