diff --git a/config/Rules.am b/config/Rules.am
index 168cecea2cfc..fbbca81e6500 100644
--- a/config/Rules.am
+++ b/config/Rules.am
@@ -21,7 +21,8 @@ endif
 
 AM_LIBTOOLFLAGS = --silent
 
-AM_CFLAGS  = -std=gnu99 -Wall -Wstrict-prototypes -fno-strict-aliasing
+AM_CFLAGS  = -std=gnu99 -Wall -Wstrict-prototypes -Wmissing-prototypes
+AM_CFLAGS += -fno-strict-aliasing
 AM_CFLAGS += $(NO_OMIT_FRAME_POINTER)
 AM_CFLAGS += $(DEBUG_CFLAGS)
 AM_CFLAGS += $(ASAN_CFLAGS)
diff --git a/module/Kbuild.in b/module/Kbuild.in
index b42ce9e6dacf..120ce87c58c7 100644
--- a/module/Kbuild.in
+++ b/module/Kbuild.in
@@ -16,6 +16,7 @@ ifneq ($(KERNELRELEASE),)
 obj-$(CONFIG_ZFS) := $(ZFS_MODULES)
 
 ZFS_MODULE_CFLAGS += -std=gnu99 -Wno-declaration-after-statement
+ZFS_MODULE_CFLAGS += -Wmissing-prototypes
 ZFS_MODULE_CFLAGS += @KERNEL_DEBUG_CFLAGS@  @NO_FORMAT_ZERO_LENGTH@
 
 ifneq ($(KBUILD_EXTMOD),)
diff --git a/module/Makefile.bsd b/module/Makefile.bsd
index 92b5c1906c1c..d23cacd36218 100644
--- a/module/Makefile.bsd
+++ b/module/Makefile.bsd
@@ -303,80 +303,44 @@ beforeinstall:
 CFLAGS.gcc+= -Wno-pointer-to-int-cast
 
 CFLAGS.lapi.c= -Wno-cast-qual
-CFLAGS.lcompat.c= -Wno-cast-qual -Wno-missing-prototypes
+CFLAGS.lcompat.c= -Wno-cast-qual
 CFLAGS.lobject.c= -Wno-cast-qual
 CFLAGS.ltable.c= -Wno-cast-qual
 CFLAGS.lvm.c= -Wno-cast-qual
 CFLAGS.nvpair.c= -Wno-cast-qual
-CFLAGS.acl_common.c= -Wno-strict-prototypes -Wno-missing-prototypes
-CFLAGS.callb.c= -Wno-strict-prototypes -Wno-missing-prototypes
-CFLAGS.spl_kstat.c= -Wno-missing-prototypes
 CFLAGS.spl_string.c= -Wno-cast-qual
-CFLAGS.spl_vm.c= -Wno-cast-qual -Wno-missing-prototypes
+CFLAGS.spl_vm.c= -Wno-cast-qual
 CFLAGS.spl_zlib.c= -Wno-cast-qual
 CFLAGS.abd.c= -Wno-cast-qual
-CFLAGS.freebsd_dmu.c= -Wno-missing-prototypes
-CFLAGS.freebsd_kmod.c= -Wno-missing-prototypes
-CFLAGS.vdev_geom.c= -Wno-missing-prototypes
-CFLAGS.zfs_acl.c= -Wno-missing-prototypes
-CFLAGS.zfs_ctldir.c= -Wno-missing-prototypes -Wno-strict-prototypes
 CFLAGS.zfs_log.c= -Wno-cast-qual
-CFLAGS.zfs_vfsops.c= -Wno-missing-prototypes
-CFLAGS.zfs_vnops.c= -Wno-missing-prototypes  -Wno-strict-prototypes -Wno-pointer-arith
-CFLAGS.zfs_znode.c= -Wno-missing-prototypes
-CFLAGS.zvol.c= -Wno-missing-prototypes
+CFLAGS.zfs_vnops.c= -Wno-pointer-arith
 CFLAGS.u8_textprep.c= -Wno-cast-qual
 CFLAGS.zfs_fletcher.c= -Wno-cast-qual -Wno-pointer-arith
 CFLAGS.zfs_fletcher_intel.c= -Wno-cast-qual -Wno-pointer-arith
 CFLAGS.zfs_fletcher_sse.c= -Wno-cast-qual -Wno-pointer-arith
 CFLAGS.zfs_fletcher_avx512.c= -Wno-cast-qual -Wno-pointer-arith
 CFLAGS.zprop_common.c= -Wno-cast-qual
-CFLAGS.arc.c= -Wno-missing-prototypes
-CFLAGS.blkptr.c= -Wno-missing-prototypes
-CFLAGS.dbuf.c= -Wno-missing-prototypes
-CFLAGS.dbuf_stats.c= -Wno-missing-prototypes
-CFLAGS.ddt.c= -Wno-missing-prototypes -Wno-cast-qual
-CFLAGS.dmu.c= -Wno-missing-prototypes -Wno-cast-qual
-CFLAGS.dmu_object.c= -Wno-missing-prototypes
-CFLAGS.dmu_objset.c= -Wno-missing-prototypes
+CFLAGS.ddt.c= -Wno-cast-qual
+CFLAGS.dmu.c= -Wno-cast-qual
 CFLAGS.dmu_traverse.c= -Wno-cast-qual
-CFLAGS.dsl_dir.c= -Wno-missing-prototypes -Wno-cast-qual
-CFLAGS.dsl_crypt.c= -Wno-missing-prototypes
+CFLAGS.dsl_dir.c= -Wno-cast-qual
 CFLAGS.dsl_deadlist.c= -Wno-cast-qual
-CFLAGS.dsl_pool.c= -Wno-missing-prototypes
 CFLAGS.dsl_prop.c= -Wno-cast-qual
-CFLAGS.dsl_scan.c= -Wno-missing-prototypes
 CFLAGS.fm.c= -Wno-cast-qual
-CFLAGS.gzip.c= -Wno-missing-prototypes
-CFLAGS.lzjb.c= -Wno-missing-prototypes
-CFLAGS.lz4.c= -Wno-missing-prototypes -Wno-cast-qual
-CFLAGS.metaslab.c= -Wno-missing-prototypes
-CFLAGS.sa.c= -Wno-missing-prototypes
-CFLAGS.sha256.c= -Wno-missing-prototypes
-CFLAGS.skein_zfs.c= -Wno-missing-prototypes
-CFLAGS.spa.c= -Wno-missing-prototypes -Wno-cast-qual
-CFLAGS.spa_boot.c= -Wno-missing-prototypes
-CFLAGS.spa_misc.c= -Wno-missing-prototypes -Wno-cast-qual
-CFLAGS.space_map.c= -Wno-missing-prototypes
-CFLAGS.vdev.c= -Wno-missing-prototypes
-CFLAGS.vdev_indirect.c= -Wno-missing-prototypes
-CFLAGS.vdev_label.c= -Wno-missing-prototypes
-CFLAGS.vdev_queue.c= -Wno-missing-prototypes
+CFLAGS.lz4.c= -Wno-cast-qual
+CFLAGS.spa.c= -Wno-cast-qual
+CFLAGS.spa_misc.c= -Wno-cast-qual
 CFLAGS.vdev_raidz.c= -Wno-cast-qual
 CFLAGS.vdev_raidz_math.c= -Wno-cast-qual
-CFLAGS.vdev_raidz_math_scalar.c= -Wno-cast-qual -Wno-missing-prototypes
+CFLAGS.vdev_raidz_math_scalar.c= -Wno-cast-qual
 CFLAGS.vdev_raidz_math_avx2.c= -Wno-cast-qual -Wno-duplicate-decl-specifier
 CFLAGS.vdev_raidz_math_avx512f.c= -Wno-cast-qual -Wno-duplicate-decl-specifier
 CFLAGS.vdev_raidz_math_sse2.c= -Wno-cast-qual -Wno-duplicate-decl-specifier
 CFLAGS.zap_leaf.c= -Wno-cast-qual
-CFLAGS.zap_micro.c= -Wno-missing-prototypes -Wno-cast-qual
+CFLAGS.zap_micro.c= -Wno-cast-qual
 CFLAGS.zcp.c= -Wno-cast-qual
-CFLAGS.zcp_get.c= -Wno-missing-prototypes
-CFLAGS.zfs_debug.c= -Wno-missing-prototypes
 CFLAGS.zfs_fm.c= -Wno-cast-qual
-CFLAGS.zfs_ioctl.c= -Wno-missing-prototypes -Wno-cast-qual
-CFLAGS.zil.c= -Wno-missing-prototypes -Wno-cast-qual
-CFLAGS.zio.c= -Wno-missing-prototypes -Wno-cast-qual
-CFLAGS.zio_checksum.c= -Wno-missing-prototypes
-CFLAGS.zle.c= -Wno-missing-prototypes
-CFLAGS.zrlock.c= -Wno-missing-prototypes -Wno-cast-qual
+CFLAGS.zfs_ioctl.c= -Wno-cast-qual
+CFLAGS.zil.c= -Wno-cast-qual
+CFLAGS.zio.c= -Wno-cast-qual
+CFLAGS.zrlock.c= -Wno-cast-qual