diff --git a/Makefile b/Makefile
index 62e49d0..53ba66e 100644
--- a/Makefile
+++ b/Makefile
@@ -70,5 +70,21 @@ install-spank: spank
 	$(INSTALL) -d $(DESTDIR)/$(libdir)/slurm
 	$(INSTALL) msrsave/libspank_msrsafe.so $(DESTDIR)/$(libdir)/slurm/libspank_msrsafe.so
 
+# The current spack package ignore this Makefile for building the
+# msr-safe.ko kernel module, as it is building against an arbitrary
+# version of the linux kernel and thus $(shell uname -r) is not useful.
+#
+# Installation relies on the spack package setting DESTDIR to the
+# msr-safe package prefix spec variable.
+#
+# Later iterations of the spack package might also build and install
+# msrsave.  That will likely require a reworking of this Makefile.
+# Prefer single-source-of-truth in that case.
+spack-install:
+	$(INSTALL) -d $(DESTDIR)/lib/modules
+	$(INSTALL) msr-safe.ko $(DESTDIR)/lib/modules
+	$(INSTALL) -d $(DESTDIR)/include
+	$(INSTALL) msr_safe.h $(DESTDIR)/include
+
 .SUFFIXES: .c .o
 .PHONY: all clean install spank install-spank
diff --git a/msr-smp.c b/msr-smp.c
index 34310e5..15a0b75 100644
--- a/msr-smp.c
+++ b/msr-smp.c
@@ -18,6 +18,7 @@
 #include <linux/smp.h>
 
 #include "msr_safe.h"
+#include "msr-smp.h"
 
 static void __msr_safe_batch(void *info)
 {
diff --git a/msr-smp.h b/msr-smp.h
new file mode 100644
index 0000000..3dc2ad4
--- /dev/null
+++ b/msr-smp.h
@@ -0,0 +1,12 @@
+// Copyright 2011-2021 Lawrence Livermore National Security, LLC and other
+// msr-safe Project Developers. See the top-level COPYRIGHT file for
+// details.
+//
+// SPDX-License-Identifier: GPL-2.0-only
+
+#ifndef MSR_SMP_INCLUDE
+#define MSR_SMP_INCLUDE
+
+int msr_safe_batch(struct msr_batch_array *oa);
+
+#endif
diff --git a/msr_allowlist.c b/msr_allowlist.c
index f815d05..fb5936a 100644
--- a/msr_allowlist.c
+++ b/msr_allowlist.c
@@ -16,6 +16,8 @@
 #include <linux/uaccess.h>
 #include <linux/version.h>
 
+#include "msr_allowlist.h"
+
 #define MAX_WLIST_BSIZE ((128 * 1024) + 1) // "+1" for null character
 
 struct allowlist_entry
diff --git a/msr_allowlist.h b/msr_allowlist.h
index 7e0e94d..1eda4a4 100644
--- a/msr_allowlist.h
+++ b/msr_allowlist.h
@@ -20,7 +20,7 @@
 
 int msr_allowlist_init(int *majordev);
 
-int msr_allowlist_cleanup(int majordev);
+void msr_allowlist_cleanup(int majordev);
 
 int msr_allowlist_exists(void);
 
diff --git a/msr_batch.c b/msr_batch.c
index 56feb15..dd46c27 100644
--- a/msr_batch.c
+++ b/msr_batch.c
@@ -31,6 +31,7 @@
 
 #include "msr_batch.h"
 #include "msr_safe.h"
+#include "msr-smp.h"
 #include "msr_allowlist.h"
 
 static struct class *cdev_class;
@@ -73,8 +74,6 @@ static int msrbatch_apply_allowlist(struct msr_batch_array *oa)
     return err;
 }
 
-extern int msr_safe_batch(struct msr_batch_array *oa);
-
 static long msrbatch_ioctl(struct file *f, unsigned int ioc, unsigned long arg)
 {
     int err = 0;
diff --git a/msr_version.c b/msr_version.c
index 5abe857..bee1832 100644
--- a/msr_version.c
+++ b/msr_version.c
@@ -12,6 +12,8 @@
 #include <linux/module.h>
 #include <linux/uaccess.h>
 
+#include "msr_version.h"
+
 static struct class *cdev_class;
 static char cdev_created;
 static char cdev_registered;
diff --git a/msr_version.h b/msr_version.h
index ff9d68d..1f66aae 100644
--- a/msr_version.h
+++ b/msr_version.h
@@ -20,6 +20,6 @@
 
 int msr_version_init(int *majordev);
 
-int msr_version_cleanup(int majordev);
+void msr_version_cleanup(int majordev);
 
 #endif