diff --git a/alliance/src/s2r/configure.in b/alliance/src/s2r/configure.in
index 8f2165e6..788e9042 100644
--- a/alliance/src/s2r/configure.in
+++ b/alliance/src/s2r/configure.in
@@ -23,6 +23,7 @@ AC_PROG_MAKE_SET
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST
+AC_CHECK_LIB(m, sqrt)
 
 AM_ALLIANCE