diff --git a/faircmakemodules.sh b/faircmakemodules.sh
index 490b512c..581239cf 100644
--- a/faircmakemodules.sh
+++ b/faircmakemodules.sh
@@ -6,6 +6,11 @@ build_requires:
   - CMake
   - "GCC-Toolchain:(?!osx)"
   - alibuild-recipe-tools
+prefer_system_check: |
+    if [ ! -z "$FAIRCMAKEMODULES_VERSION" ]; then
+        exit 0
+    fi
+    exit 1
 ---
 #!/bin/sh
 
diff --git a/geant4_vmc.sh b/geant4_vmc.sh
index 572c4b49..039a4fb5 100644
--- a/geant4_vmc.sh
+++ b/geant4_vmc.sh
@@ -19,10 +19,8 @@ prefer_system_check: |
   ls $GEANT4_VMC_ROOT/bin > /dev/null && \
   ls $GEANT4_VMC_ROOT/lib/libg4root.so > /dev/null && \
   ls $GEANT4_VMC_ROOT/lib/libgeant4vmc.so> /dev/null && \
-  ls $GEANT4_VMC_ROOT/lib/libmtroot.so > /dev/null && \
   ls $GEANT4_VMC_ROOT/include/g4root > /dev/null && \
   ls $GEANT4_VMC_ROOT/include/geant4vmc > /dev/null && \
-  ls $GEANT4_VMC_ROOT/include/mtroot > /dev/null && \
   true
 ---
 #!/bin/bash -e
diff --git a/rootegpythia6.sh b/rootegpythia6.sh
index 4b69e0fc..4918e4ca 100644
--- a/rootegpythia6.sh
+++ b/rootegpythia6.sh
@@ -13,6 +13,11 @@ prepend_path:
   LD_LIBRARY_PATH: "$ROOTEGPYTHIA6_ROOT/lib"
   ROOT_INCLUDE_PATH: "$ROOTEGPYTHIA6_ROOT/include"
   CMAKE_MODULE_PATH: "$ROOTEGPYTHIA6_ROOT/lib/cmake/ROOTEGPythia6/Modules"
+prefer_system_check: |
+    if [ ! -z "$ROOTEGPYTHIA6_VERSION" ]; then
+        exit 0
+    fi
+    exit 1
 ---
 #!/bin/bash -e