diff --git a/extensions/Makefile.am b/extensions/Makefile.am
index 2c1fe26..56f9471 100644
--- a/extensions/Makefile.am
+++ b/extensions/Makefile.am
@@ -10,7 +10,7 @@ modules:
 	${AM_V_silent}if [ -n "${kbuilddir}" ]; then ${MAKE} ${_kcall} modules; fi;
 
 modules_install:
-	${AM_V_silent}if [ -n "${kbuilddir}" ]; then ${MAKE} ${_kcall} INSTALL_MOD_PATH=${DESTDIR} modules_install; fi;
+	${AM_V_silent}if [ -n "${kbuilddir}" ]; then ${MAKE} ${_kcall} INSTALL_MOD_PATH=${DESTDIR} ext-mod-dir='$${INSTALL_MOD_DIR}' modules_install; fi;
 
 clean_modules:
 	${AM_V_silent}if [ -n "${kbuilddir}" ]; then ${MAKE} ${_kcall} clean; fi;