diff --git a/share/completions/dmesg.fish b/share/completions/dmesg.fish
index 0b17de138..aa71bbdc8 100644
--- a/share/completions/dmesg.fish
+++ b/share/completions/dmesg.fish
@@ -1,20 +1,51 @@
-set -l levels '( __fish_complete_list , "echo emerg\nalert\ncrit\nerr\nwarn\nnotice\ninfo\ndebug" )'
-complete -c dmesg -s C -l clear               -d 'Clear the kernel ring buffer'
-complete -c dmesg -s c -l read-clear          -d 'Read and clear all messages'
-complete -c dmesg -s D -l console-off         -d 'Disable printing messages to console'
-complete -c dmesg -s d -l show-delta          -d 'Show time delta between printed messages'
-complete -c dmesg -s E -l console-on          -d 'Enable printing messages to console'
-complete -c dmesg -s F -l file                -d 'Use the file instead of the kernel log buffer'
-complete -c dmesg -s f -l facility            -d 'Restrict output to defined facilities' -xa '( __fish_complete_list , "echo kern\nuser\nmail\ndaemon\nauth\nsyslog\nlpr\nnews" )'
-complete -c dmesg -s h -l help                -d 'Display this help and exit'
-complete -c dmesg -s k -l kernel              -d 'Display kernel messages'
-complete -c dmesg -s l -l level               -d 'Restrict output to defined levels' -xa $levels
-complete -c dmesg -s n -l console-level       -d 'Set level of messages printed to console' -xa $levels
-complete -c dmesg -s r -l raw                 -d 'Print the raw message buffer'
-complete -c dmesg -s s -l buffer-size         -d 'Buffer size to query the kernel ring buffer' -x
-complete -c dmesg -s T -l ctime               -d 'Show human readable timestamp '
-complete -c dmesg -s t -l notime              -d 'Don\'t print messages timestamp'
-complete -c dmesg -s u -l userspace           -d 'Display userspace messages'
-complete -c dmesg -s V -l version             -d 'Output version information and exit'
-complete -c dmesg -s x -l decode              -d 'Decode facility and level to readable string'
+complete -c dmesg -f -d 'Display system message buffer'
 
+switch (uname -s)
+	#
+	# Solaris
+	#
+	case SunOS
+		exit 1 # no options, we are done
+	#
+	# Loonix dmesg
+	#
+	case Linux
+		set -l levels '( __fish_complete_list , "echo emerg\nalert\ncrit\nerr\nwarn\nnotice\ninfo\ndebug" )'
+		complete -c dmesg -s C -l clear               -f -d'Clear kernel ring buffer'
+		complete -c dmesg -s c -l read-clear          -f -d'Read & clear all msgs'
+		complete -c dmesg -s D -l console-off         -f -d'Disable writing to console'
+		complete -c dmesg -s d -l show-delta          -f -d'Show timestamp deltas'
+		complete -c dmesg -s E -l console-on          -f -d'Enable writing to console'
+		complete -c dmesg -s F -l file             -r    -d'Use file instead of log buffer'
+		complete -c dmesg -s f -l facility      -x       -d'Only print for given facilities' -a '( __fish_complete_list , "echo kern\nuser\nmail\ndaemon\nauth\nsyslog\nlpr\nnews" )'
+		complete -c dmesg -s h -l help                -f -d'Display help'
+		complete -c dmesg -s k -l kernel              -f -d'Print kernel messages'
+		complete -c dmesg -s l -l level         -x       -d'Restrict output to given levels' -a $levels
+		complete -c dmesg -s n -l console-level -x       -d'Adjust threshold to print to console' -a $levels
+		complete -c dmesg -s r -l raw                 -f -d'Print raw message buffer'
+		complete -c dmesg -s s -l buffer-size   -x       -d'Buffer size to query kernel'
+		complete -c dmesg -s T -l ctime               -f -d'Human-readable timestamps'
+		complete -c dmesg -s t -l notime              -f -d'Don\'t print timestamps'
+		complete -c dmesg -s u -l userspace           -f -d'Print userspace messages'
+		complete -c dmesg -s V -l version             -f -d'Show dmesg version'
+		complete -c dmesg -s x -l decode              -f -d'Decode facility & level numbers'
+		exit 0 # done
+	#
+	# unique options specific BSDs have
+	#
+	case NetBSD
+		complete -c dmesg -s d                        -f -d'show timestamp deltas'
+		complete -c dmesg -s T                        -f -d'human-readable timestamps'
+		complete -c dmesg -s t                        -f -d'don\'t print timestamps'
+	case OpenBSD
+		complete -c dmesg -s S                        -f -d'display console message buffer-size'
+	case FreeBSD DragonFly
+		complete -c dmesg -s a                        -f -d'print all data in the message buffer'
+		complete -c dmesg -s c                        -f -d'clear kernel buffer after printing'
+end
+
+#
+# common BSD dmesg options (macOS only does these two)
+#
+complete 		 -c dmesg -s M                      -r   -d'get namelist values from given core'
+complete 		 -c dmesg -s N                      -r   -d'get namelist from given kernel'