diff --git a/configure.ac b/configure.ac
index 7fdcf5af1..46421fdb7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1375,6 +1375,9 @@ AC_MSG_RESULT([$XNEST])
 AM_CONDITIONAL(XNEST, [test "x$XNEST" = xyes])
 
 if test "x$XNEST" = xyes; then
+	if test "x$have_xnest" = xno; then
+		AC_MSG_ERROR([Xnest build explicitly requested, but required modules not found.])
+	fi
 	XNEST_LIBS="$FB_LIB $FIXES_LIB $MI_LIB $XEXT_LIB $DBE_LIB $RECORD_LIB $GLX_LIBS $RANDR_LIB $RENDER_LIB $DAMAGE_LIB $MIEXT_DAMAGE_LIB $MIEXT_SHADOW_LIB $XI_LIB $XKB_LIB $XKB_STUB_LIB $COMPOSITE_LIB $DIX_LIB $MAIN_LIB $OS_LIB $CONFIG_LIB"
 	XNEST_SYS_LIBS="$XNESTMODULES_LIBS $GLX_SYS_LIBS"
 	AC_SUBST([XNEST_LIBS])