diff --git a/src/auto/configure b/src/auto/configure
index e07d7ec..ed8ca6a 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -5207,6 +5207,7 @@
 
   if test "X$with_plthome" != "X"; then
        vi_cv_path_mzscheme_pfx="$with_plthome"
+       vi_cv_path_mzscheme="${vi_cv_path_mzscheme_pfx}/bin/mzscheme"
   else
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking PLTHOME environment var" >&5
 $as_echo_n "checking PLTHOME environment var... " >&6; }
@@ -5214,6 +5215,7 @@
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: \"$PLTHOME\"" >&5
 $as_echo "\"$PLTHOME\"" >&6; }
 	vi_cv_path_mzscheme_pfx="$PLTHOME"
+	vi_cv_path_mzscheme="${vi_cv_path_mzscheme_pfx}/bin/mzscheme"
     else
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: not set" >&5
 $as_echo "not set" >&6; }
@@ -5285,54 +5287,63 @@
     fi
   fi
 
-  SCHEME_INC=
   if test "X$vi_cv_path_mzscheme_pfx" != "X"; then
-    { $as_echo "$as_me:${as_lineno-$LINENO}: checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include" >&5
-$as_echo_n "checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include... " >&6; }
-    if test -f "$vi_cv_path_mzscheme_pfx/include/scheme.h"; then
-      SCHEME_INC=${vi_cv_path_mzscheme_pfx}/include
-      { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for racket include directory" >&5
+$as_echo_n "checking for racket include directory... " >&6; }
+    SCHEME_INC=`${vi_cv_path_mzscheme} -e '(require setup/dirs)(let ((p (find-include-dir))) (when (path? p) (display p)))'`
+    if test "X$SCHEME_INC" != "X"; then
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: ${SCHEME_INC}" >&5
+$as_echo "${SCHEME_INC}" >&6; }
     else
-      { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include/plt" >&5
-$as_echo_n "checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include/plt... " >&6; }
-      if test -f "$vi_cv_path_mzscheme_pfx/include/plt/scheme.h"; then
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: not found" >&5
+$as_echo "not found" >&6; }
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include" >&5
+$as_echo_n "checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include... " >&6; }
+      if test -f "$vi_cv_path_mzscheme_pfx/include/scheme.h"; then
+	SCHEME_INC=${vi_cv_path_mzscheme_pfx}/include
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-	SCHEME_INC=${vi_cv_path_mzscheme_pfx}/include/plt
       else
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
-	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include/racket" >&5
-$as_echo_n "checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include/racket... " >&6; }
-	if test -f "$vi_cv_path_mzscheme_pfx/include/racket/scheme.h"; then
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include/plt" >&5
+$as_echo_n "checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include/plt... " >&6; }
+	if test -f "$vi_cv_path_mzscheme_pfx/include/plt/scheme.h"; then
 	  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-	  SCHEME_INC=${vi_cv_path_mzscheme_pfx}/include/racket
+	  SCHEME_INC=${vi_cv_path_mzscheme_pfx}/include/plt
 	else
 	  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
-	  { $as_echo "$as_me:${as_lineno-$LINENO}: checking if scheme.h can be found in /usr/include/plt/" >&5
-$as_echo_n "checking if scheme.h can be found in /usr/include/plt/... " >&6; }
-	  if test -f /usr/include/plt/scheme.h; then
+	  { $as_echo "$as_me:${as_lineno-$LINENO}: checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include/racket" >&5
+$as_echo_n "checking if scheme.h can be found in $vi_cv_path_mzscheme_pfx/include/racket... " >&6; }
+	  if test -f "$vi_cv_path_mzscheme_pfx/include/racket/scheme.h"; then
 	    { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-	    SCHEME_INC=/usr/include/plt
+	    SCHEME_INC=${vi_cv_path_mzscheme_pfx}/include/racket
 	  else
 	    { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
-	    { $as_echo "$as_me:${as_lineno-$LINENO}: checking if scheme.h can be found in /usr/include/racket/" >&5
-$as_echo_n "checking if scheme.h can be found in /usr/include/racket/... " >&6; }
-	    if test -f /usr/include/racket/scheme.h; then
+	    { $as_echo "$as_me:${as_lineno-$LINENO}: checking if scheme.h can be found in /usr/include/plt/" >&5
+$as_echo_n "checking if scheme.h can be found in /usr/include/plt/... " >&6; }
+	    if test -f /usr/include/plt/scheme.h; then
 	      { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-	      SCHEME_INC=/usr/include/racket
+	      SCHEME_INC=/usr/include/plt
 	    else
 	      { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
-	      vi_cv_path_mzscheme_pfx=
+	      { $as_echo "$as_me:${as_lineno-$LINENO}: checking if scheme.h can be found in /usr/include/racket/" >&5
+$as_echo_n "checking if scheme.h can be found in /usr/include/racket/... " >&6; }
+	      if test -f /usr/include/racket/scheme.h; then
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+		SCHEME_INC=/usr/include/racket
+	      else
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+		vi_cv_path_mzscheme_pfx=
+	      fi
 	    fi
 	  fi
 	fi
@@ -5341,52 +5352,101 @@
   fi
 
   if test "X$vi_cv_path_mzscheme_pfx" != "X"; then
-    if test "x$MACOSX" = "xyes"; then
-      MZSCHEME_LIBS="-framework Racket"
-      MZSCHEME_CFLAGS="-DMZ_PRECISE_GC"
-    elif test -f "${vi_cv_path_mzscheme_pfx}/lib/libmzscheme3m.a"; then
-      MZSCHEME_LIBS="${vi_cv_path_mzscheme_pfx}/lib/libmzscheme3m.a"
-      MZSCHEME_CFLAGS="-DMZ_PRECISE_GC"
-    elif test -f "${vi_cv_path_mzscheme_pfx}/lib/libracket3m.a"; then
-      MZSCHEME_LIBS="${vi_cv_path_mzscheme_pfx}/lib/libracket3m.a"
-      MZSCHEME_CFLAGS="-DMZ_PRECISE_GC"
-    elif test -f "${vi_cv_path_mzscheme_pfx}/lib/libracket.a"; then
-      MZSCHEME_LIBS="${vi_cv_path_mzscheme_pfx}/lib/libracket.a ${vi_cv_path_mzscheme_pfx}/lib/libmzgc.a"
-    elif test -f "${vi_cv_path_mzscheme_pfx}/lib/libmzscheme.a"; then
-      MZSCHEME_LIBS="${vi_cv_path_mzscheme_pfx}/lib/libmzscheme.a ${vi_cv_path_mzscheme_pfx}/lib/libmzgc.a"
+
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for racket lib directory" >&5
+$as_echo_n "checking for racket lib directory... " >&6; }
+    SCHEME_LIB=`${vi_cv_path_mzscheme} -e '(require setup/dirs)(let ((p (find-lib-dir))) (when (path? p) (display p)))'`
+    if test "X$SCHEME_LIB" != "X"; then
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: ${SCHEME_LIB}" >&5
+$as_echo "${SCHEME_LIB}" >&6; }
     else
-            if test -f "${vi_cv_path_mzscheme_pfx}/lib/libmzscheme3m.so"; then
-        MZSCHEME_LIBS="-L${vi_cv_path_mzscheme_pfx}/lib -lmzscheme3m"
-	MZSCHEME_CFLAGS="-DMZ_PRECISE_GC"
-      elif test -f "${vi_cv_path_mzscheme_pfx}/lib/libracket3m.so"; then
-        MZSCHEME_LIBS="-L${vi_cv_path_mzscheme_pfx}/lib -lracket3m"
-	MZSCHEME_CFLAGS="-DMZ_PRECISE_GC"
-      elif test -f "${vi_cv_path_mzscheme_pfx}/lib/libracket.so"; then
-        MZSCHEME_LIBS="-L${vi_cv_path_mzscheme_pfx}/lib -lracket -lmzgc"
-      else
-        MZSCHEME_LIBS="-L${vi_cv_path_mzscheme_pfx}/lib -lmzscheme -lmzgc"
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: not found" >&5
+$as_echo "not found" >&6; }
+    fi
+
+    for path in "${vi_cv_path_mzscheme_pfx}/lib" "${SCHEME_LIB}"; do
+      if test "X$path" != "X"; then
+	if test "x$MACOSX" = "xyes"; then
+	  MZSCHEME_LIBS="-framework Racket"
+	  MZSCHEME_CFLAGS="-DMZ_PRECISE_GC"
+	elif test -f "${path}/libmzscheme3m.a"; then
+	  MZSCHEME_LIBS="${path}/libmzscheme3m.a"
+	  MZSCHEME_CFLAGS="-DMZ_PRECISE_GC"
+	elif test -f "${path}/libracket3m.a"; then
+	  MZSCHEME_LIBS="${path}/libracket3m.a"
+	  MZSCHEME_CFLAGS="-DMZ_PRECISE_GC"
+	elif test -f "${path}/libracket.a"; then
+	  MZSCHEME_LIBS="${path}/libracket.a ${path}/libmzgc.a"
+	elif test -f "${path}/libmzscheme.a"; then
+	  MZSCHEME_LIBS="${path}/libmzscheme.a ${path}/libmzgc.a"
+	else
+	  	  if test -f "${path}/libmzscheme3m.so"; then
+	    MZSCHEME_LIBS="-L${path} -lmzscheme3m"
+	    MZSCHEME_CFLAGS="-DMZ_PRECISE_GC"
+	  elif test -f "${path}/libracket3m.so"; then
+	    MZSCHEME_LIBS="-L${path} -lracket3m"
+	    MZSCHEME_CFLAGS="-DMZ_PRECISE_GC"
+	  elif test -f "${path}/libracket.so"; then
+	    MZSCHEME_LIBS="-L${path} -lracket -lmzgc"
+	  else
+	    	    if test "$path" != "$SCHEME_LIB"; then
+	      continue
+	    fi
+	    MZSCHEME_LIBS="-L${path} -lmzscheme -lmzgc"
+	  fi
+	  if test "$GCC" = yes; then
+	    	    	    MZSCHEME_LIBS="${MZSCHEME_LIBS} -Wl,-rpath -Wl,${path}"
+	  elif test "`(uname) 2>/dev/null`" = SunOS &&
+				   uname -r | grep '^5' >/dev/null; then
+	    MZSCHEME_LIBS="${MZSCHEME_LIBS} -R ${path}"
+	  fi
+	fi
       fi
-      if test "$GCC" = yes; then
-			MZSCHEME_LIBS="${MZSCHEME_LIBS} -Wl,-rpath -Wl,${vi_cv_path_mzscheme_pfx}/lib"
-      elif test "`(uname) 2>/dev/null`" = SunOS &&
-			       uname -r | grep '^5' >/dev/null; then
-	MZSCHEME_LIBS="${MZSCHEME_LIBS} -R ${vi_cv_path_mzscheme_pfx}/lib"
+      if test "X$MZSCHEME_LIBS" != "X"; then
+	break
       fi
+    done
+
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking if racket requires -pthread" >&5
+$as_echo_n "checking if racket requires -pthread... " >&6; }
+    if test "X$SCHEME_LIB" != "X" && $FGREP -e -pthread "$SCHEME_LIB/buildinfo" >/dev/null ; then
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+      MZSCHEME_LIBS="${MZSCHEME_LIBS} -pthread"
+      MZSCHEME_CFLAGS="${MZSCHEME_CFLAGS} -pthread"
+    else
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+    fi
+
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for racket config directory" >&5
+$as_echo_n "checking for racket config directory... " >&6; }
+    SCHEME_CONFIGDIR=`${vi_cv_path_mzscheme} -e '(require setup/dirs)(let ((p (find-config-dir))) (when (path? p) (display p)))'`
+    if test "X$SCHEME_CONFIGDIR" != "X"; then
+      MZSCHEME_CFLAGS="${MZSCHEME_CFLAGS} -DMZSCHEME_CONFIGDIR='\"${SCHEME_CONFIGDIR}\"'"
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: ${SCHEME_CONFIGDIR}" >&5
+$as_echo "${SCHEME_CONFIGDIR}" >&6; }
+    else
+      { $as_echo "$as_me:${as_lineno-$LINENO}: result: not found" >&5
+$as_echo "not found" >&6; }
     fi
 
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for racket collects directory" >&5
 $as_echo_n "checking for racket collects directory... " >&6; }
-    if test -d "$vi_cv_path_mzscheme_pfx/lib/plt/collects"; then
-      SCHEME_COLLECTS=$vi_cv_path_mzscheme_pfx/lib/plt/
-    else
-      if test -d "$vi_cv_path_mzscheme_pfx/lib/racket/collects"; then
-	SCHEME_COLLECTS=$vi_cv_path_mzscheme_pfx/lib/racket/
+    SCHEME_COLLECTS=`${vi_cv_path_mzscheme} -e '(require setup/dirs)(let ((p (find-collects-dir))) (when (path? p) (let-values (((base _1 _2) (split-path p))) (display base))))'`
+    if test "X$SCHEME_COLLECTS" = "X"; then
+      if test -d "$vi_cv_path_mzscheme_pfx/lib/plt/collects"; then
+	SCHEME_COLLECTS=$vi_cv_path_mzscheme_pfx/lib/plt/
       else
-	if test -d "$vi_cv_path_mzscheme_pfx/share/racket/collects"; then
-	  SCHEME_COLLECTS=$vi_cv_path_mzscheme_pfx/share/racket/
+	if test -d "$vi_cv_path_mzscheme_pfx/lib/racket/collects"; then
+	  SCHEME_COLLECTS=$vi_cv_path_mzscheme_pfx/lib/racket/
 	else
-	  if test -d "$vi_cv_path_mzscheme_pfx/collects"; then
-	    SCHEME_COLLECTS=$vi_cv_path_mzscheme_pfx/
+	  if test -d "$vi_cv_path_mzscheme_pfx/share/racket/collects"; then
+	    SCHEME_COLLECTS=$vi_cv_path_mzscheme_pfx/share/racket/
+	  else
+	    if test -d "$vi_cv_path_mzscheme_pfx/collects"; then
+	      SCHEME_COLLECTS=$vi_cv_path_mzscheme_pfx/
+	    fi
 	  fi
 	fi
       fi
@@ -5420,7 +5480,6 @@
     fi
     if test "X$MZSCHEME_EXTRA" != "X" ; then
             MZSCHEME_CFLAGS="${MZSCHEME_CFLAGS} -DINCLUDE_MZSCHEME_BASE"
-      MZSCHEME_MZC="${vi_cv_path_mzscheme_pfx}/bin/mzc"
       { $as_echo "$as_me:${as_lineno-$LINENO}: result: needed" >&5
 $as_echo "needed" >&6; }
     else