diff --git a/lib/scripts/getsettings b/lib/scripts/getsettings
--- a/lib/scripts/getsettings
+++ b/lib/scripts/getsettings
@@ -1,125 +1,125 @@
 # -*- shell-script -*- :mode=shellscript:
 #
 # Author: Makarius
 #
 # Static Isabelle environment for root of process tree.
 
 export ISABELLE_HOME
 
 export BASH_ENV="$ISABELLE_HOME/lib/scripts/getfunctions"
 source "$BASH_ENV"
 
 
 if [ -z "$ISABELLE_SETTINGS_PRESENT" ]
 then
 
 export ISABELLE_SETTINGS_PRESENT=true
 
 set -o allexport
 
 #sane environment defaults (notably on Mac OS X)
 if [ "$ISABELLE_APP" = true -a -x /usr/libexec/path_helper ]; then
   eval $(/usr/libexec/path_helper -s)
 fi
 
 #Cygwin vs. POSIX
 if [ "$OSTYPE" = cygwin ]
 then
   unset INI_DIR
 
   if [ -n "$TEMP_WINDOWS" ]; then
     TMPDIR="$(cygpath -u "$TEMP_WINDOWS")"
     TMP="$TMPDIR"
     TEMP="$TMPDIR"
   fi
 
   if [ -z "$USER_HOME" ]; then
     USER_HOME="$(cygpath -u "$USERPROFILE")"
   fi
 
   CYGWIN_ROOT="$(platform_path "/")"
   ISABELLE_ROOT="$(platform_path "$ISABELLE_HOME")"
 
   ISABELLE_CLASSPATH="$(cygpath -i -u -p "$CLASSPATH")"
   unset CLASSPATH
 else
   if [ -z "$USER_HOME" ]; then
     USER_HOME="$HOME"
   fi
 
   ISABELLE_ROOT="$ISABELLE_HOME"
 
   ISABELLE_CLASSPATH="$CLASSPATH"
   unset CLASSPATH
 fi
 
 #main executables
 ISABELLE_TOOL="$ISABELLE_HOME/bin/isabelle"
 ISABELLE_SCALA_SCRIPT="$ISABELLE_HOME/bin/isabelle_scala_script"
 PATH="$ISABELLE_HOME/bin:$PATH"
 
 #platform
 source "$ISABELLE_HOME/lib/scripts/isabelle-platform"
-if [ -z "$ISABELLE_PLATFORM" ]; then
+if [ -z "$ISABELLE_PLATFORM32" -a -z "$ISABELLE_PLATFORM64" ]; then
   echo 1>&2 "Failed to determine hardware and operating system type!"
   exit 2
 fi
 
 #Isabelle distribution identifier -- filled in automatically!
 ISABELLE_ID=""
 [ -z "$ISABELLE_IDENTIFIER" ] && ISABELLE_IDENTIFIER=""
 
 
 # components
 
 ISABELLE_COMPONENTS=""
 ISABELLE_COMPONENTS_MISSING=""
 
 #main components
 init_component "$ISABELLE_HOME"
 [ -d "$ISABELLE_HOME/Admin" ] && init_component "$ISABELLE_HOME/Admin"
 if [ -d "$ISABELLE_HOME_USER" ]; then
   init_component "$ISABELLE_HOME_USER"
 else
   mkdir -p "$ISABELLE_HOME_USER"
   chmod $(umask -S) "$ISABELLE_HOME_USER"
 fi
 
 #POLYML_EXE
 if [ "$ISABELLE_PLATFORM_FAMILY" = "windows" ]; then
   POLYML_EXE="$ML_HOME/poly.exe"
 else
   POLYML_EXE="$ML_HOME/poly"
 fi
 
 #ML system identifier
 if [ -z "$ML_PLATFORM" ]; then
   ML_IDENTIFIER="$ML_SYSTEM"
 else
   ML_IDENTIFIER="${ML_SYSTEM}_${ML_PLATFORM}"
 fi
 
 #enforce ISABELLE_OCAMLFIND
 if [ -d "$ISABELLE_OPAM_ROOT/$ISABELLE_OCAML_VERSION/bin" ]; then
   ISABELLE_OCAMLFIND="$ISABELLE_HOME/lib/scripts/ocamlfind"
 fi
 
 #enforce ISABELLE_GHC
 if [ -f "$ISABELLE_STACK_ROOT/ISABELLE_GHC_EXE-$ISABELLE_PLATFORM_FAMILY" ]; then
   if [ -f "$(cat "$ISABELLE_STACK_ROOT/ISABELLE_GHC_EXE-$ISABELLE_PLATFORM_FAMILY")" ]; then
     ISABELLE_GHC="$ISABELLE_HOME/lib/scripts/ghc"
     ISABELLE_GHC_STACK=true
   fi
 fi
 
 #enforce JAVA_HOME
 if [ -d "$ISABELLE_JDK_HOME/jre" ]
 then
   export JAVA_HOME="$ISABELLE_JDK_HOME/jre"
 else
   export JAVA_HOME="$ISABELLE_JDK_HOME"
 fi
 
 set +o allexport
 
 fi
diff --git a/lib/scripts/isabelle-platform b/lib/scripts/isabelle-platform
--- a/lib/scripts/isabelle-platform
+++ b/lib/scripts/isabelle-platform
@@ -1,60 +1,43 @@
 # -*- shell-script -*- :mode=shellscript:
 #
 # determine general hardware and operating system type for Isabelle system tools
 #
 
 ISABELLE_PLATFORM_FAMILY=""
 ISABELLE_PLATFORM32=""
 ISABELLE_PLATFORM64=""
 ISABELLE_WINDOWS_PLATFORM32=""
 ISABELLE_WINDOWS_PLATFORM64=""
 
 case $(uname -s) in
   Linux)
     ISABELLE_PLATFORM_FAMILY="linux"
-    case $(uname -m) in
-      i?86)
-        ISABELLE_PLATFORM32=x86-linux
-        ;;
-      x86_64)
-        ISABELLE_PLATFORM32=x86-linux
-        ISABELLE_PLATFORM64=x86_64-linux
-        ;;
-    esac
+    ISABELLE_PLATFORM32=x86-linux
+    ISABELLE_PLATFORM64=x86_64-linux
     ;;
   Darwin)
     ISABELLE_PLATFORM_FAMILY="macos"
-    case $(uname -m) in
-      i?86)
+    case $(sw_vers -productVersion) in
+      10.10*|10.11*|10.12*|10.13*|10.14*)
         ISABELLE_PLATFORM32=x86-darwin
-        if [ "$(sysctl -n hw.optional.x86_64 2>/dev/null)" = 1 ]; then
-          ISABELLE_PLATFORM64=x86_64-darwin
-        fi
+        ISABELLE_PLATFORM64=x86_64-darwin
         ;;
-      x86_64)
-        ISABELLE_PLATFORM32=x86-darwin
+      *)
         ISABELLE_PLATFORM64=x86_64-darwin
         ;;
     esac
     ;;
   CYGWIN_NT*)
     ISABELLE_PLATFORM_FAMILY="windows"
-    if [ "$PROCESSOR_ARCHITECTURE" = "AMD64" -o "$PROCESSOR_ARCHITEW6432" = "AMD64" ]; then
-      ISABELLE_WINDOWS_PLATFORM32="x86-windows"
-      ISABELLE_WINDOWS_PLATFORM64="x86_64-windows"
-    else
-      ISABELLE_WINDOWS_PLATFORM32="x86-windows"
-    fi
+    ISABELLE_WINDOWS_PLATFORM32="x86-windows"
+    ISABELLE_WINDOWS_PLATFORM64="x86_64-windows"
     case $(uname -m) in
       x86_64)
         ISABELLE_PLATFORM64=x86_64-cygwin
         ;;
       i?86)
         ISABELLE_PLATFORM32=x86-cygwin
         ;;
     esac
     ;;
 esac
-
-ISABELLE_PLATFORM="${ISABELLE_PLATFORM32:-$ISABELLE_PLATFORM64}"
-ISABELLE_WINDOWS_PLATFORM="${ISABELLE_WINDOWS_PLATFORM32:-$ISABELLE_WINDOWS_PLATFORM64}"