diff --git a/configure.in b/configure.in
index bb632a38c..436a25839 100644
--- a/configure.in
+++ b/configure.in
@@ -1,7 +1,7 @@
 dnl -*- sh -*-
 dnl the "configure" script is made from this by running GNU "autoconf"
 dnl
-dnl "$Id: configure.in,v 1.33.2.31.2.10 2001/10/18 18:53:20 easysw Exp $"
+dnl "$Id: configure.in,v 1.33.2.31.2.11 2001/10/18 20:47:10 easysw Exp $"
 dnl
 dnl Configuration script for the Fast Light Tool Kit (FLTK).
 dnl
@@ -319,6 +319,14 @@ if test "$mandir" = "\${prefix}/man" -a "$prefix" = "/usr"; then
 fi
 
 dnl Fix "libdir" variable...
+if test "$prefix" = NONE; then
+	prefix=/usr/local
+fi
+
+if test "$exec_prefix" = NONE; then
+	exec_prefix="$prefix"
+fi
+
 if test "$uname" = "IRIX" -a $uversion -ge 62 -a "$libdir" = "\${exec_prefix}/lib" -a "$exec_prefix" = "/usr"; then
 	libdir="/usr/lib32"
 fi
@@ -466,5 +474,5 @@ AC_OUTPUT(makeinclude fltk-config)
 chmod +x fltk-config
 
 dnl
-dnl End of "$Id: configure.in,v 1.33.2.31.2.10 2001/10/18 18:53:20 easysw Exp $".
+dnl End of "$Id: configure.in,v 1.33.2.31.2.11 2001/10/18 20:47:10 easysw Exp $".
 dnl