diff --git a/maintainer/CI/build_cmake.sh b/maintainer/CI/build_cmake.sh
index ca678efb564..8448d39ad1f 100755
--- a/maintainer/CI/build_cmake.sh
+++ b/maintainer/CI/build_cmake.sh
@@ -58,14 +58,14 @@ function set_default_value {
     if [ "${default}" = true -o "${default}" = false ]; then
         # cast boolean values to true/false
         local -r val=$(echo "${value}" | tr '[:upper:]' '[:lower:]')
-        if [ "${val}" = false -o "${val}" = "off" -o "${val}" = 0 ]; then
+        if [ "${val}" = false -o "${val}" = "off" -o "${val}" = 0 -o "${val}" = "no" ]; then
             eval "${varname}=false"
-        elif [ "${val}" = true -o "${val}" = "on" -o "${val}" = 1 ]; then
+        elif [ "${val}" = true -o "${val}" = "on" -o "${val}" = 1 -o "${val}" = "yes" ]; then
             eval "${varname}=true"
         elif [ -z "${val}" ]; then
             eval "${varname}='${default}'"
         else
-            echo "Cannot cast '${value}' to boolean"
+            echo "Cannot interpret '${value}' as a true/false value in variable '${varname}'"
             exit 1
         fi
     elif [ -z "${value}" ]; then
diff --git a/maintainer/CI/build_docker.sh b/maintainer/CI/build_docker.sh
index d187d4e12cb..b444c4209ca 100755
--- a/maintainer/CI/build_docker.sh
+++ b/maintainer/CI/build_docker.sh
@@ -6,7 +6,7 @@ cat > $ENV_FILE <<EOF
 insource=$insource
 cmake_params=$cmake_params
 with_fftw=$with_fftw
-with_python_interface=yes
+with_python_interface=true
 with_coverage=$with_coverage
 myconfig=$myconfig
 check_procs=$check_procs
@@ -15,7 +15,7 @@ python_version=$python_version
 EOF
 
 if [ -z "$image" ]; then
-	image=ubuntu
+    image=ubuntu
 fi
 
 image=espressomd/espresso-$image:latest