diff --git a/Admin/isatest/settings/mac-poly64-M4 b/Admin/isatest/settings/mac-poly64-M4
--- a/Admin/isatest/settings/mac-poly64-M4
+++ b/Admin/isatest/settings/mac-poly64-M4
@@ -1,30 +1,31 @@
 # -*- shell-script -*- :mode=shellscript:
 
 init_components /home/isabelle/contrib "$HOME/admin/components/main"
 
   POLYML_HOME="/home/polyml/polyml-5.4.1"
   ML_SYSTEM="polyml-5.4.1"
   ML_PLATFORM="x86_64-darwin"
   ML_HOME="$POLYML_HOME/$ML_PLATFORM"
   ML_OPTIONS="-H 2000 --gcthreads 4"
 
-ISABELLE_GHC=ghc
+#FIXME disabled due to polyml-5.4.1 compiler crash in Quickcheck_Lattice_Examples.thy
+#ISABELLE_GHC=ghc
 
 ISABELLE_HOME_USER=~/isabelle-mac-poly64-M4
 
 # Where to look for isabelle tools (multiple dirs separated by ':').
 ISABELLE_TOOLS="$ISABELLE_HOME/lib/Tools"
 
 # Location for temporary files (should be on a local file system).
 ISABELLE_TMP_PREFIX="/tmp/isabelle-$USER"
 
 
 # Heap input locations. ML system identifier is included in lookup.
 ISABELLE_PATH="$ISABELLE_HOME_USER/heaps:$ISABELLE_HOME/heaps"
 
 # Heap output location. ML system identifier is appended automatically later on.
 ISABELLE_OUTPUT="$ISABELLE_HOME_USER/heaps"
 ISABELLE_BROWSER_INFO="$ISABELLE_HOME_USER/browser_info"
 
 ISABELLE_BUILD_OPTIONS="browser_info=false document=false threads=4 parallel_proofs=2"
 
diff --git a/Admin/isatest/settings/mac-poly64-M8 b/Admin/isatest/settings/mac-poly64-M8
--- a/Admin/isatest/settings/mac-poly64-M8
+++ b/Admin/isatest/settings/mac-poly64-M8
@@ -1,30 +1,31 @@
 # -*- shell-script -*- :mode=shellscript:
 
 init_components /home/isabelle/contrib "$HOME/admin/components/main"
 
   POLYML_HOME="/home/polyml/polyml-5.4.1"
   ML_SYSTEM="polyml-5.4.1"
   ML_PLATFORM="x86_64-darwin"
   ML_HOME="$POLYML_HOME/$ML_PLATFORM"
   ML_OPTIONS="-H 2000 --gcthreads 8"
 
-ISABELLE_GHC=ghc
+#FIXME disabled due to polyml-5.4.1 compiler crash in Quickcheck_Lattice_Examples.thy
+#ISABELLE_GHC=ghc
 
 ISABELLE_HOME_USER=~/isabelle-mac-poly64-M8
 
 # Where to look for isabelle tools (multiple dirs separated by ':').
 ISABELLE_TOOLS="$ISABELLE_HOME/lib/Tools"
 
 # Location for temporary files (should be on a local file system).
 ISABELLE_TMP_PREFIX="/tmp/isabelle-$USER"
 
 
 # Heap input locations. ML system identifier is included in lookup.
 ISABELLE_PATH="$ISABELLE_HOME_USER/heaps:$ISABELLE_HOME/heaps"
 
 # Heap output location. ML system identifier is appended automatically later on.
 ISABELLE_OUTPUT="$ISABELLE_HOME_USER/heaps"
 ISABELLE_BROWSER_INFO="$ISABELLE_HOME_USER/browser_info"
 
 ISABELLE_BUILD_OPTIONS="browser_info=false document=false threads=8 parallel_proofs=2"