diff --git a/src/Makefile b/src/Makefile
index 8197b12..5a4ca88 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -875,6 +875,10 @@
 #CFLAGS = -O -Qtarget=m88110compat
 #EXTRA_LIBS = -lgen
 
+# The value of QUOTESED comes from auto/config.mk.
+# Uncomment the next line to use the default value.
+# QUOTESED = sed -e 's/[\\"]/\\&/g' -e 's/\\"/"/' -e 's/\\";$$/";/'
+
 ##################### end of system specific lines ################### }}}
 
 ### Names of the programs and targets  {{{1
@@ -2411,7 +2415,6 @@
 auto/osdef.h: auto/config.h osdef.sh osdef1.h.in osdef2.h.in
 	CC="$(CC) $(OSDEF_CFLAGS)" srcdir=$(srcdir) sh $(srcdir)/osdef.sh
 
-QUOTESED = sed -e 's/[\\"]/\\&/g' -e 's/\\"/"/' -e 's/\\";$$/";/'
 auto/pathdef.c: Makefile auto/config.mk
 	-@echo creating $@
 	-@echo '/* pathdef.c */' > $@
diff --git a/src/auto/configure b/src/auto/configure
index 3321f49..ae0d121 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -4426,15 +4426,18 @@
 		  echo ""
 		  echo "------------------------------------------"
 		  echo " On z/OS Unix, the environment variable"
-		  echo " __CC_${ccn}MODE must be set to \"1\"!"
+		  echo " _CC_${ccn}MODE must be set to \"1\"!"
 		  echo " Do:"
 		  echo "    export _CC_${ccn}MODE=1"
 		  echo " and then call configure again."
 		  echo "------------------------------------------"
 		  exit 1
 		fi
-		CFLAGS="$CFLAGS -D_ALL_SOURCE -Wc,float\\(IEEE\\)";
-                LDFLAGS="$LDFLAGS -Wl,EDIT=NO"
+		# Set CFLAGS for configure process.
+		# This will be reset later for config.mk.
+		# Use haltonmsg to force error for missing H files.
+		CFLAGS="$CFLAGS -D_ALL_SOURCE -Wc,float(ieee),haltonmsg(3296)";
+		LDFLAGS="$LDFLAGS -Wl,EDIT=NO"
 		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
 		;;
@@ -8697,8 +8700,13 @@
 if test -z "$SKIP_MOTIF"; then
   cppflags_save=$CPPFLAGS
   CPPFLAGS="$CPPFLAGS $X_CFLAGS"
-  for ac_header in Xm/Xm.h Xm/XpmP.h Xm/JoinSideT.h Xm/TraitP.h Xm/Manager.h \
-		   Xm/UnhighlightT.h Xm/Notebook.h
+  if test "$zOSUnix" = "yes"; then
+	xmheader="Xm/Xm.h"
+  else
+	xmheader="Xm/Xm.h Xm/XpmP.h Xm/JoinSideT.h Xm/TraitP.h Xm/Manager.h
+  	   Xm/UnhighlightT.h Xm/Notebook.h"
+  fi
+  for ac_header in $xmheader
 do :
   as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
 ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
@@ -8713,7 +8721,7 @@
 done
 
 
-  if test $ac_cv_header_Xm_XpmP_h = yes; then
+  if test "x$ac_cv_header_Xm_XpmP_h" = "xyes"; then
         { $as_echo "$as_me:${as_lineno-$LINENO}: checking for XpmAttributes_21 in Xm/XpmP.h" >&5
 $as_echo_n "checking for XpmAttributes_21 in Xm/XpmP.h... " >&6; }
     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -12590,6 +12598,11 @@
 fi
 
 
+# IBM z/OS reset CFLAGS for config.mk
+if test "$zOSUnix" = "yes"; then
+	CFLAGS="-D_ALL_SOURCE -Wc,float\(ieee\),dll"
+fi
+
 ac_config_files="$ac_config_files auto/config.mk:config.mk.in"
 
 cat >confcache <<\_ACEOF
diff --git a/src/configure.in b/src/configure.in
index 2ede332..7439904 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -329,15 +329,18 @@
 		  echo ""
 		  echo "------------------------------------------"
 		  echo " On z/OS Unix, the environment variable"
-		  echo " __CC_${ccn}MODE must be set to \"1\"!"
+		  echo " _CC_${ccn}MODE must be set to \"1\"!"
 		  echo " Do:"
 		  echo "    export _CC_${ccn}MODE=1"
 		  echo " and then call configure again."
 		  echo "------------------------------------------"
 		  exit 1
 		fi
-		CFLAGS="$CFLAGS -D_ALL_SOURCE -Wc,float\\(IEEE\\)";
-                LDFLAGS="$LDFLAGS -Wl,EDIT=NO"
+		# Set CFLAGS for configure process.
+		# This will be reset later for config.mk.
+		# Use haltonmsg to force error for missing H files.
+		CFLAGS="$CFLAGS -D_ALL_SOURCE -Wc,float(ieee),haltonmsg(3296)";
+		LDFLAGS="$LDFLAGS -Wl,EDIT=NO"
 		AC_MSG_RESULT(yes)
 		;;
     *)		zOSUnix="no";
@@ -2378,10 +2381,15 @@
 if test -z "$SKIP_MOTIF"; then
   cppflags_save=$CPPFLAGS
   CPPFLAGS="$CPPFLAGS $X_CFLAGS"
-  AC_CHECK_HEADERS(Xm/Xm.h Xm/XpmP.h Xm/JoinSideT.h Xm/TraitP.h Xm/Manager.h \
-		   Xm/UnhighlightT.h Xm/Notebook.h)
+  if test "$zOSUnix" = "yes"; then
+	xmheader="Xm/Xm.h"
+  else
+	xmheader="Xm/Xm.h Xm/XpmP.h Xm/JoinSideT.h Xm/TraitP.h Xm/Manager.h
+  	   Xm/UnhighlightT.h Xm/Notebook.h"  
+  fi    
+  AC_CHECK_HEADERS($xmheader)
 
-  if test $ac_cv_header_Xm_XpmP_h = yes; then
+  if test "x$ac_cv_header_Xm_XpmP_h" = "xyes"; then
     dnl Solaris uses XpmAttributes_21, very annoying.
     AC_MSG_CHECKING([for XpmAttributes_21 in Xm/XpmP.h])
     AC_TRY_COMPILE([#include <Xm/XpmP.h>], [XpmAttributes_21 attr;],
@@ -3642,6 +3650,11 @@
 fi
 AC_SUBST(LINK_AS_NEEDED)
 
+# IBM z/OS reset CFLAGS for config.mk
+if test "$zOSUnix" = "yes"; then
+	CFLAGS="-D_ALL_SOURCE -Wc,float\(ieee\),dll"
+fi
+
 dnl write output files
 AC_OUTPUT(auto/config.mk:config.mk.in)
 
diff --git a/src/version.c b/src/version.c
index 9ef28d4..d3bb184 100644
--- a/src/version.c
+++ b/src/version.c
@@ -715,6 +715,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    555,
+/**/
     554,
 /**/
     553,