diff --git a/doc_src/index.hdr.in b/doc_src/index.hdr.in
index a4f1271d6..df1d01288 100644
--- a/doc_src/index.hdr.in
+++ b/doc_src/index.hdr.in
@@ -1235,12 +1235,12 @@ Note that functions cannot be started in the background. Functions that are stop
 On startup, Fish evaluates a number of configuration files, which can be used to control the behavior of the shell. The location of these configuration variables is controlled by a number of environment variables, and their default or usual location is given below.
 
 Configuration files are evaluated in the following order:
-- Configuration shipped with fish, which should not be edited, in `$__fish_datadir/config.fish` (usually `/usr/share/fish/config.fish`).
-- System-wide configuration files, where administrators can include initialization that should be run for all users on the system - similar to `/etc/profile` for POSIX-style shells - in `$__fish_sysconfdir` (usually `/etc/fish/config.fish`);
+- Configuration shipped with fish, which should not be edited, in `$__fish_data_dir/config.fish` (usually `/usr/share/fish/config.fish`).
+- System-wide configuration files, where administrators can include initialization that should be run for all users on the system - similar to `/etc/profile` for POSIX-style shells - in `$__fish_sysconf_dir` (usually `/etc/fish/config.fish`);
 - Configuration snippets in files ending in `.fish`, in the directories:
   - `$XDG_CONFIG_HOME/fish/conf.d` (by default, `~/.config/fish/conf.d/`)
-  - `$__fish_sysconfdir/conf.d` (by default, `/etc/fish/conf.d`)
-  - `/usr/share/fish/vendor_conf.d` (set at compile time; by default, `$__fish_datadir/conf.d`)
+  - `$__fish_sysconf_dir/conf.d` (by default, `/etc/fish/conf.d`)
+  - `/usr/share/fish/vendor_conf.d` (set at compile time; by default, `$__fish_data_dir/conf.d`)
 
   If there are multiple files with the same name in these directories, only the first will be executed.
   They are executed in order of their filename, sorted (like globs) in a natural order (i.e. "01" sorts before "2").
diff --git a/share/completions/help.fish b/share/completions/help.fish
index 1acc9898c..4f5547a8c 100644
--- a/share/completions/help.fish
+++ b/share/completions/help.fish
@@ -1,4 +1,4 @@
-if test -d "$__fish_datadir/man/man1/"
+if test -d "$__fish_data_dir/man/man1/"
 	complete -c help -x -a '(__fish_print_commands)' -d 'Help for this command'
 end
 
diff --git a/share/config.fish b/share/config.fish
index c24039d7b..85d7ba09a 100644
--- a/share/config.fish
+++ b/share/config.fish
@@ -25,7 +25,7 @@ if status --is-interactive
         # These "XXX nostring" hacks were added for 2.3.1
         set_color --bold
         echo "You appear to be trying to launch an old fish binary with newer scripts "
-        echo "installed into" (set_color --underline)"$__fish_datadir"
+        echo "installed into" (set_color --underline)"$__fish_data_dir"
         set_color normal
         echo -e "\nThis is an unsupported configuration.\n"
         set_color yellow
@@ -74,7 +74,7 @@ if set -q XDG_DATA_HOME
     set userdatadir $XDG_DATA_HOME
 end
 
-# __fish_datadir, __fish_sysconfdir, __fish_help_dir, __fish_bin_dir
+# __fish_data_dir, __fish_sysconf_dir, __fish_help_dir, __fish_bin_dir
 # are expected to have been set up by read_init from fish.cpp
 
 # Grab extra directories (as specified by the build process, usually for
@@ -82,27 +82,27 @@ end
 set -l __extra_completionsdir
 set -l __extra_functionsdir
 set -l __extra_confdir
-if test -f $__fish_datadir/__fish_build_paths.fish
-    source $__fish_datadir/__fish_build_paths.fish
+if test -f $__fish_data_dir/__fish_build_paths.fish
+    source $__fish_data_dir/__fish_build_paths.fish
 end
 
 # Set up function and completion paths. Make sure that the fish
 # default functions/completions are included in the respective path.
 
 if not set -q fish_function_path
-    set fish_function_path $configdir/fish/functions $__fish_sysconfdir/functions $__extra_functionsdir $__fish_datadir/functions
+    set fish_function_path $configdir/fish/functions $__fish_sysconf_dir/functions $__extra_functionsdir $__fish_data_dir/functions
 end
 
-if not contains -- $__fish_datadir/functions $fish_function_path
-    set fish_function_path $fish_function_path $__fish_datadir/functions
+if not contains -- $__fish_data_dir/functions $fish_function_path
+    set fish_function_path $fish_function_path $__fish_data_dir/functions
 end
 
 if not set -q fish_complete_path
-    set fish_complete_path $configdir/fish/completions $__fish_sysconfdir/completions $__extra_completionsdir $__fish_datadir/completions $userdatadir/fish/generated_completions
+    set fish_complete_path $configdir/fish/completions $__fish_sysconf_dir/completions $__extra_completionsdir $__fish_data_dir/completions $userdatadir/fish/generated_completions
 end
 
-if not contains -- $__fish_datadir/completions $fish_complete_path
-    set fish_complete_path $fish_complete_path $__fish_datadir/completions
+if not contains -- $__fish_data_dir/completions $fish_complete_path
+    set fish_complete_path $fish_complete_path $__fish_data_dir/completions
 end
 
 #
@@ -222,7 +222,7 @@ __fish_set_locale
 # As last part of initialization, source the conf directories.
 # Implement precedence (User > Admin > Extra (e.g. vendors) > Fish) by basically doing "basename".
 set -l sourcelist
-for file in $configdir/fish/conf.d/*.fish $__fish_sysconfdir/conf.d/*.fish $__extra_confdir/*.fish
+for file in $configdir/fish/conf.d/*.fish $__fish_sysconf_dir/conf.d/*.fish $__extra_confdir/*.fish
     set -l basename (string replace -r '^.*/' '' -- $file)
     contains -- $basename $sourcelist
     and continue
diff --git a/share/functions/__fish_complete_man.fish b/share/functions/__fish_complete_man.fish
index 7fa40fd06..5061e5271 100644
--- a/share/functions/__fish_complete_man.fish
+++ b/share/functions/__fish_complete_man.fish
@@ -70,7 +70,7 @@ function __fish_complete_man
 
         # Fish commands are not given by apropos
         if not set -ql exclude_fish_commands
-          set -l files $__fish_datadir/man/man1/*.1
+          set -l files $__fish_data_dir/man/man1/*.1
           string replace -r '.*/([^/]+)\.1$' '$1\t1: fish command' -- $files
         end
     else
diff --git a/share/functions/__fish_config_interactive.fish b/share/functions/__fish_config_interactive.fish
index 958db0c09..44f49b284 100644
--- a/share/functions/__fish_config_interactive.fish
+++ b/share/functions/__fish_config_interactive.fish
@@ -131,7 +131,7 @@ function __fish_config_interactive -d "Initializations that should be performed
             # We don't want to call `fish -c` since that is unnecessary and sources config.fish again.
             # Hence we'll call python directly.
             # c_m_p.py should work with any python version.
-            set -l update_args -B $__fish_datadir/tools/create_manpage_completions.py --manpath --cleanup-in '~/.config/fish/completions' --cleanup-in '~/.config/fish/generated_completions'
+            set -l update_args -B $__fish_data_dir/tools/create_manpage_completions.py --manpath --cleanup-in '~/.config/fish/completions' --cleanup-in '~/.config/fish/generated_completions'
             if command -qs python3
                 python3 $update_args >/dev/null ^/dev/null &
             else if command -qs python2
diff --git a/share/functions/__fish_print_commands.fish b/share/functions/__fish_print_commands.fish
index bac2bd732..9eb15c858 100644
--- a/share/functions/__fish_print_commands.fish
+++ b/share/functions/__fish_print_commands.fish
@@ -1,6 +1,6 @@
 function __fish_print_commands --description "Print a list of documented fish commands"
-    if test -d $__fish_datadir/man/man1/
-        for file in $__fish_datadir/man/man1/**.1*
+    if test -d $__fish_data_dir/man/man1/
+        for file in $__fish_data_dir/man/man1/**.1*
             string replace -r '.*/' '' -- $file | string replace -r '.1(.gz)?$' ''
         end
     end
diff --git a/share/functions/__fish_print_help.fish b/share/functions/__fish_print_help.fish
index 5c9604a7b..5f51b46e4 100644
--- a/share/functions/__fish_print_help.fish
+++ b/share/functions/__fish_print_help.fish
@@ -11,7 +11,7 @@ function __fish_print_help --description "Print help message for the specified f
     end
 
     # Do nothing if the file does not exist
-    if not test -e "$__fish_datadir/man/man1/$item.1" -o -e "$__fish_datadir/man/man1/$item.1.gz"
+    if not test -e "$__fish_data_dir/man/man1/$item.1" -o -e "$__fish_data_dir/man/man1/$item.1.gz"
         return
     end
 
@@ -37,15 +37,15 @@ function __fish_print_help --description "Print help message for the specified f
         set cols (math $cols - 4) # leave a bit of space on the right
         set rLL -rLL=$cols[1]n
     end
-    set -lx GROFF_TMAC_PATH $__fish_datadir/groff
+    set -lx GROFF_TMAC_PATH $__fish_data_dir/groff
     set -l mfish
     if test -e $GROFF_TMAC_PATH/fish.tmac
         set mfish -mfish
     end
-    if test -e "$__fish_datadir/man/man1/$item.1"
-        set help (nroff -c -man $mfish -t $rLL "$__fish_datadir/man/man1/$item.1" ^/dev/null)
-    else if test -e "$__fish_datadir/man/man1/$item.1.gz"
-        set help (gunzip -c "$__fish_datadir/man/man1/$item.1.gz" ^/dev/null | nroff -c -man $mfish -t $rLL ^/dev/null)
+    if test -e "$__fish_data_dir/man/man1/$item.1"
+        set help (nroff -c -man $mfish -t $rLL "$__fish_data_dir/man/man1/$item.1" ^/dev/null)
+    else if test -e "$__fish_data_dir/man/man1/$item.1.gz"
+        set help (gunzip -c "$__fish_data_dir/man/man1/$item.1.gz" ^/dev/null | nroff -c -man $mfish -t $rLL ^/dev/null)
     end
 
     # The original implementation trimmed off the top 5 lines and bottom 3 lines
diff --git a/share/functions/fish_config.fish b/share/functions/fish_config.fish
index 4684fc351..fa6c54e46 100644
--- a/share/functions/fish_config.fish
+++ b/share/functions/fish_config.fish
@@ -1,10 +1,10 @@
 function fish_config --description "Launch fish's web based configuration"
     set -lx __fish_bin_dir $__fish_bin_dir
     if command -sq python3
-        python3 "$__fish_datadir/tools/web_config/webconfig.py" $argv
+        python3 "$__fish_data_dir/tools/web_config/webconfig.py" $argv
     else if command -sq python2
-        python2 "$__fish_datadir/tools/web_config/webconfig.py" $argv
+        python2 "$__fish_data_dir/tools/web_config/webconfig.py" $argv
     else if command -sq python
-        python "$__fish_datadir/tools/web_config/webconfig.py" $argv
+        python "$__fish_data_dir/tools/web_config/webconfig.py" $argv
     end
 end
diff --git a/share/functions/fish_update_completions.fish b/share/functions/fish_update_completions.fish
index 5cec0a4bf..014a5a9cd 100644
--- a/share/functions/fish_update_completions.fish
+++ b/share/functions/fish_update_completions.fish
@@ -9,7 +9,7 @@ function fish_update_completions --description "Update man-page based completion
     end
 
     # Clean up old paths
-    set -l update_args -B $__fish_datadir/tools/create_manpage_completions.py --manpath --cleanup-in '~/.config/fish/completions' --cleanup-in '~/.config/fish/generated_completions' --progress
+    set -l update_args -B $__fish_data_dir/tools/create_manpage_completions.py --manpath --cleanup-in '~/.config/fish/completions' --cleanup-in '~/.config/fish/generated_completions' --progress
     if command -qs python3
         python3 $update_args
     else if command -qs python2
diff --git a/share/functions/help.fish b/share/functions/help.fish
index 6e8a0e429..e04aed808 100644
--- a/share/functions/help.fish
+++ b/share/functions/help.fish
@@ -110,7 +110,7 @@ function help --description 'Show help for the fish shell'
                 # Prefer to use fish's man pages, to avoid
                 # the annoying useless "builtin" man page bash
                 # installs on OS X
-                set -l man_arg "$__fish_datadir/man/man1/$fish_help_item.1"
+                set -l man_arg "$__fish_data_dir/man/man1/$fish_help_item.1"
                 if test -f "$man_arg"
                     man $man_arg
                     return
@@ -164,7 +164,7 @@ function help --description 'Show help for the fish shell'
         # by using a custom style sheet. See https://github.com/fish-shell/fish-shell/issues/4170
         set -l local_file 0
         if eval $fish_browser --version 2>/dev/null | string match -qr Lynx
-            set fish_browser $fish_browser -lss={$__fish_datadir}/lynx.lss
+            set fish_browser $fish_browser -lss={$__fish_data_dir}/lynx.lss
         end
         eval $fish_browser $page_url
     end
diff --git a/share/functions/man.fish b/share/functions/man.fish
index e0cacf4d9..6cc21b8c0 100644
--- a/share/functions/man.fish
+++ b/share/functions/man.fish
@@ -12,7 +12,7 @@ function man --description "Format and display the on-line manual pages"
     # Notice local exported copy of the variable.
     set -lx MANPATH $manpath
 
-    set -l fish_manpath (dirname $__fish_datadir)/fish/man
+    set -l fish_manpath (dirname $__fish_data_dir)/fish/man
     if test -d "$fish_manpath" -a -n "$MANPATH"
         set MANPATH $fish_manpath:$MANPATH
         # Invoke man with this manpath, and we're done.
diff --git a/src/env.cpp b/src/env.cpp
index 2e3defd55..6ff150668 100644
--- a/src/env.cpp
+++ b/src/env.cpp
@@ -63,8 +63,8 @@
 #define DEFAULT_TERM2 "dumb"
 
 /// Some configuration path environment variables.
-#define FISH_DATADIR_VAR L"__fish_datadir"
-#define FISH_SYSCONFDIR_VAR L"__fish_sysconfdir"
+#define FISH_DATADIR_VAR L"__fish_data_dir"
+#define FISH_SYSCONFDIR_VAR L"__fish_sysconf_dir"
 #define FISH_HELPDIR_VAR L"__fish_help_dir"
 #define FISH_BIN_DIR L"__fish_bin_dir"