diff --git a/config/zsh/all/env b/config/zsh/all/env
new file mode 100644
index 0000000..eb9ccf2
--- /dev/null
+++ b/config/zsh/all/env
@@ -0,0 +1,5 @@
+#! zsh
+# We can't inherit the uniqueness flag -U through the environment, so it must
+# be established in every Zsh to guarantee these parameters actually contain
+# only unique values.
+typeset -U cdpath fpath mailpath manpath path pythonpath
diff --git a/config/zsh/login/fpath b/config/zsh/login/fpath
index 6fd6bbd..6d4a6c2 100644
--- a/config/zsh/login/fpath
+++ b/config/zsh/login/fpath
@@ -1,5 +1,7 @@
 #! zsh
 fpath=($ZDOTDIR/functions $fpath)
 
-# filter out duplicates, nonexistent directories, and . (the current directory)
 fpath=(${(u)^fpath:#.}(N))
+# FPATH isn't exported by default like PATH is - to inherit the setting in
+# non-login shells, we need to export it ourselves.
+typeset -x FPATH
diff --git a/config/zsh/login/path b/config/zsh/login/path
index f92409a..0bfad87 100644
--- a/config/zsh/login/path
+++ b/config/zsh/login/path
@@ -1,7 +1,6 @@
 #! zsh
-
 path=(/usr/local/bin $path)
-if whence brew >/dev/null; then
+if (( $+commands[brew] )); then
 	path=(
 		/usr/local/opt/coreutils/libexec/gnubin
 		/usr/local/sbin
@@ -13,5 +12,6 @@ fi
 path=(/usr/local/texlive/20*/bin/universal-*(N) $path)
 path=(~/bin ~/.bin ~/.local/bin $path)
 
-# filter out duplicates, nonexistent directories, and . (the current directory)
+# Filter out nonexistent directories, . (the current directory), and duplicate
+# paths - there should be no duplicates because of -U but just to be sure. ;)
 path=(${(u)^path:#.}(N))