diff --git a/configure.ac b/configure.ac
index 451c5e0d641631dca9826e27b6bf81542cc1bd4f..4c200b48b5093e407710c5712237276c6bef4d1e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -621,7 +621,7 @@ AS_IF([test "x$with_natpmp" != xno],
 AC_DEFINE_UNQUOTED([HAVE_LIBNATPMP],
   `if test "x$with_natpmp" != xno; then echo 1; else echo 0; fi`,
   [Define if you have libnatpmp])
-AM_CONDITIONAL([BUILD_NATPMP], test "x$with_natpmp" = "xyes")
+AM_CONDITIONAL([BUILD_NATPMP], test "x$with_natpmp" != "xno")
 
 # SHM
 dnl check for shm