--- a/configure.ac
+++ b/configure.ac
@@ -58,7 +58,7 @@ AC_HEADER_STDC
 AC_CHECK_LIB(pq,PQconnectStart,,
         AC_MSG_ERROR([*** Can't find libpq]))
 
-CFLAGS=`guile-config compile`
+CFLAGS="${CFLAGS} `guile-config compile`"
 LIBS=`guile-config link`
 
 . $srcdir/DBD-VERSION
