diff --git a/src/os/Makefile.am b/src/os/Makefile.am
index 252c678..c28ad0a 100644
--- a/src/os/Makefile.am
+++ b/src/os/Makefile.am
@@ -61,7 +61,7 @@ noinst_HEADERS += \
 
 if WITH_LIBZFS
 libos_zfs_a_SOURCES = os/ZFS.cc
-libos_zfs_a_CXXFLAGS = ${AM_CXXFLAGS} ${LIBZFS_CFLAGS}
+libos_zfs_a_CXXFLAGS = ${AM_CXXFLAGS} ${LIBZFS_CFLAGS} -I/usr/include/libzfs -I/usr/include/libspl
 noinst_LIBRARIES += libos_zfs.a
 noinst_HEADERS += os/ZFS.h
 endif