diff --git a/alliance/src/l2p/configure.in b/alliance/src/l2p/configure.in
index 806ad706..2f04a31d 100644
--- a/alliance/src/l2p/configure.in
+++ b/alliance/src/l2p/configure.in
@@ -26,6 +26,8 @@ AC_PROG_MAKE_SET
 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST
 
+AC_CHECK_LIB(m, floor)
+
 AM_ALLIANCE
 
 AC_OUTPUT([