diff --git a/share/functions/__fish_apropos.fish b/share/functions/__fish_apropos.fish
index d8b203654..fb1e0196e 100644
--- a/share/functions/__fish_apropos.fish
+++ b/share/functions/__fish_apropos.fish
@@ -4,39 +4,49 @@ if not type -q apropos
     exit
 end
 
-function __fish_apropos
-    # macOS 10.15 "Catalina" has some major issues.
-    # The whatis database is non-existent, so apropos tries (and fails) to create it every time,
-    # which takes about half a second.
-    #
-    # Instead, we build a whatis database in the user cache directory
-    # and override the MANPATH using that directory before we run `apropos`
-    #
-    # the cache is rebuilt once a day
-    if test (uname) = Darwin
-        set -l cache $HOME/.cache/fish/
-        if test -n "$XDG_CACHE_HOME"
-            set cache $XDG_CACHE_HOME/fish
-        end
+# Check for macOS Catalina or above. This is Darwin 19.x or above. See unames reported here:
+# https://en.wikipedia.org/wiki/Darwin_(operating_system)
+set -l sysver (uname -sr | string match -r "(Darwin) (\d\d)"\.)
 
-        set -l db $cache/whatis
+test $status -eq 0 -a (count $sysver) -eq 3
+and if test $sysver[2] = 'Darwin' -a $sysver[3] -ge 19
+
+    if test -n "$XDG_CACHE_HOME"
+        set dir $XDG_CACHE_HOME/fish
+    else
+        set dir (getconf DARWIN_USER_CACHE_DIR)"fish"
+    end
+
+    function __fish_apropos -V dir
+        # macOS 10.15 "Catalina" has a read only filesystem where the whatis database should be.
+        # The whatis database is non-existent, so apropos tries (and fails) to create it every time,
+        # which can take seconds.
+        #
+        # Instead, we build a whatis database in the user cache directory
+        # and override the MANPATH using that directory before we run `apropos`
+        #
+        # the cache is rebuilt once a week.
+        set -l whatis $cache/whatis
         set -l max_age 86400 # one day
         set -l age $max_age
 
-        if test -f "$db"
+        if test -f "$whatis"
             # Some people use GNU tools on macOS, and GNU stat works differently.
             # However it's currently guaranteed that the macOS stat is in /usr/bin,
             # so we use that explicitly.
-            set age (math (date +%s) - (/usr/bin/stat -f %m $db))
+            set age (math (date +%s) - (/usr/bin/stat -f %m $whatis))
         end
 
-        MANPATH="$cache" apropos -- $argv
+        MANPATH="$dir" apropos $argv
 
         if test $age -ge $max_age
-            mkdir -m 700 -p $cache
-            /usr/libexec/makewhatis -o $db (man --path | string split :) >/dev/null 2>&1 </dev/null &
+            test -d "$dir" || mkdir -m 700 -p $dir
+            /usr/libexec/makewhatis -o "$whatis" (man --path | string split :) >/dev/null 2>&1 </dev/null &
         end
-    else
-        apropos -- $argv
     end
+else
+    function __fish_apropos
+        apropos $argv
+    end
+
 end