diff --git a/ChangeLog b/ChangeLog
index 8660b400..8962a94a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2001-04-02  Frank Warmerdam  <warmerdam@pobox.com>
 
+	* configure/config.site: modified to check if -lm is needed for
+	MACHDEPLIBS if not supplied by config.site.  Needed for Darwin.
+
 	* config.guess: updated wholesale to an FSF version apparently 
 	from 1998 (as opposed to 1994).  This is mainly inspired by 
 	providing for MacOS X support.
diff --git a/config.site b/config.site
index 0650e2c3..ee81b622 100644
--- a/config.site
+++ b/config.site
@@ -1,4 +1,4 @@
-# $Header: /cvs/maptools/cvsroot/libtiff/Attic/config.site,v 1.3 2001-03-30 01:55:32 warmerda Exp $
+# $Header: /cvs/maptools/cvsroot/libtiff/Attic/config.site,v 1.4 2001-04-03 03:51:57 warmerda Exp $
 #
 # TIFF Software
 #
@@ -134,7 +134,7 @@
 #GCOPTS="-g"				# options to pass C compiler
 #OPTIMIZER="-O"				# Optimization options for compiler
 #LIBPORT='${PORT}/libport.a'		# library with emulation code
-#MACHDEPLIBS=""				# extra libraries for linking
+#MACHDEPLIBS="-lm"			# extra libraries for linking
 #PORTFUNCS=""				# non-standard functions to emulate
 #RANLIB=":"				# pathname of suitable ranlib program
 #DSOSUF="so"				# DSO filename suffix
diff --git a/configure b/configure
index fa1bd2d2..635da62b 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #!/bin/sh
-#	$Header: /cvs/maptools/cvsroot/libtiff/configure,v 1.11 2001-03-30 01:55:32 warmerda Exp $
+#	$Header: /cvs/maptools/cvsroot/libtiff/configure,v 1.12 2001-04-03 03:51:57 warmerda Exp $
 #
 # Tag Image File Format (TIFF) Software
 #
@@ -57,7 +57,6 @@ PORT=auto				# enable portability emulations
 HTML=no					# install HTML documentation
 LIBGL=auto				# auto-enable build of SGI -lgl apps
 LIBIMAGE=auto				# auto-enable build of SGI -limage apps
-MACHDEPLIBS=-lm				# machine-dependent libraries for apps
 : ${CC=}				# name of C compiler to use
 : ${CCOMPILER=}				# full pathname of C compiler
 : ${OPTIMIZER=-O}			# Optimization flag
@@ -153,7 +152,7 @@ do
     -target|--target)		ac_prev=TARGET;;
     -target=*|--target=*)	TARGET="$ac_optarg" ;;
     -version|--version)
-	echo "This is TIFF configure $Revision: 1.11 $"
+	echo "This is TIFF configure $Revision: 1.12 $"
 	exit 0
 	;;
     -help|--help)		usage; exit 0;;
@@ -592,10 +591,10 @@ if [ -z "${GCOPTS-}" ]; then
     if capture $CCOMPILER $ENVOPTS -g -c dummy.c; then
 	Note "Looks like $CCOMPILER supports the -g option."
 	# NB: cannot use captureX here 'cuz we lose stderr
-	if $CCOMPILER $ENVOPTS -c -g -O dummy.c >t 2>&1 && CheckForGandO t; then
+	if $CCOMPILER $ENVOPTS -c -g $OPTIMIZER dummy.c >t 2>&1 && CheckForGandO t; then
 	    GCOPTS="-g"
 	else
-	    Note "... but not together with the -O option, not using it."
+	    Note "... but not together with the $OPTIMIZER option, not using it."
 	    GCOPTS=
 	fi
     else
@@ -764,6 +763,21 @@ CheckForFunc()
     runMake t "t:; ${CCOMPILER} ${ENVOPTS} t.c ${MACHDEPLIBS}"
 }
 
+# 
+# Verify that we have -lm.  Darwin (for instance) does not.  Add to 
+# MACHDEPLIBS if required.
+#
+
+if [ -z "${MACHDEPLIBS-}" ]; then
+    MACHDEPLIBS=""
+    if ! CheckForFunc cos ; then
+        MACHDEPLIBS="-lm"
+        echo "Defaulting MACHDEPLIBS to -lm."
+    else
+        echo "Leaving MACHDEPLIBS empty, apparently you don't need -lm."
+    fi
+fi
+
 #
 # Look for a function declaration in system include files.
 #