diff --git a/Library/Homebrew/brew.sh b/Library/Homebrew/brew.sh
index 63dac99fb1..b53a7750f2 100644
--- a/Library/Homebrew/brew.sh
+++ b/Library/Homebrew/brew.sh
@@ -51,23 +51,8 @@ HOMEBREW_CACHE="${HOMEBREW_CACHE:-${HOMEBREW_DEFAULT_CACHE}}"
 HOMEBREW_LOGS="${HOMEBREW_LOGS:-${HOMEBREW_DEFAULT_LOGS}}"
 HOMEBREW_TEMP="${HOMEBREW_TEMP:-${HOMEBREW_DEFAULT_TEMP}}"
 
-# Don't need to handle a default case.
-# HOMEBREW_LIBRARY set by bin/brew
-# shellcheck disable=SC2249,SC2154
-case "$*" in
-  --cellar)            echo "${HOMEBREW_CELLAR}"; exit 0 ;;
-  --repository|--repo) echo "${HOMEBREW_REPOSITORY}"; exit 0 ;;
-  --caskroom)          echo "${HOMEBREW_PREFIX}/Caskroom"; exit 0 ;;
-  --cache)             echo "${HOMEBREW_CACHE}"; exit 0 ;;
-  shellenv)            source "${HOMEBREW_LIBRARY}/Homebrew/cmd/shellenv.sh"; homebrew-shellenv; exit 0 ;;
-  formulae)            source "${HOMEBREW_LIBRARY}/Homebrew/cmd/formulae.sh"; homebrew-formulae; exit 0 ;;
-  casks)               source "${HOMEBREW_LIBRARY}/Homebrew/cmd/casks.sh"; homebrew-casks; exit 0 ;;
-  # falls back to cmd/prefix.rb on a non-zero return
-  --prefix*)           source "${HOMEBREW_LIBRARY}/Homebrew/prefix.sh"; homebrew-prefix "$@" && exit 0 ;;
-esac
-
 #####
-##### Next, define all helper functions.
+##### Next, define helper functions for prompting.
 #####
 
 # These variables are set from the user environment.
@@ -125,6 +110,25 @@ odie() {
   exit 1
 }
 
+# Don't need to handle a default case.
+# HOMEBREW_LIBRARY set by bin/brew
+# shellcheck disable=SC2249,SC2154
+case "$*" in
+  --cellar)            echo "${HOMEBREW_CELLAR}"; exit 0 ;;
+  --repository|--repo) echo "${HOMEBREW_REPOSITORY}"; exit 0 ;;
+  --caskroom)          echo "${HOMEBREW_PREFIX}/Caskroom"; exit 0 ;;
+  --cache)             echo "${HOMEBREW_CACHE}"; exit 0 ;;
+  shellenv)            source "${HOMEBREW_LIBRARY}/Homebrew/cmd/shellenv.sh"; homebrew-shellenv; exit 0 ;;
+  formulae)            source "${HOMEBREW_LIBRARY}/Homebrew/cmd/formulae.sh"; homebrew-formulae; exit 0 ;;
+  casks)               source "${HOMEBREW_LIBRARY}/Homebrew/cmd/casks.sh"; homebrew-casks; exit 0 ;;
+  # falls back to cmd/prefix.rb on a non-zero return
+  --prefix*)           source "${HOMEBREW_LIBRARY}/Homebrew/prefix.sh"; homebrew-prefix "$@" && exit 0 ;;
+esac
+
+#####
+##### Next, define the reset of helper functions.
+#####
+
 safe_cd() {
   cd "$@" >/dev/null || odie "Failed to cd to $*!"
 }
diff --git a/Library/Homebrew/cmd/shellenv.sh b/Library/Homebrew/cmd/shellenv.sh
index 2434efee15..03531b75be 100644
--- a/Library/Homebrew/cmd/shellenv.sh
+++ b/Library/Homebrew/cmd/shellenv.sh
@@ -4,13 +4,24 @@
 #:
 #:  The variables `HOMEBREW_PREFIX`, `HOMEBREW_CELLAR` and `HOMEBREW_REPOSITORY` are also exported to avoid querying them multiple times.
 #:  The variable `HOMEBREW_SHELLENV_PREFIX` will be exported to avoid adding duplicate entries to the environment variables.
-#:  Consider adding evaluation of this command's output to your dotfiles (e.g. `~/.profile`, `~/.bash_profile`, or `~/.zprofile`) with: `eval $(brew shellenv)`
+#:
+#:  Consider adding evaluation of this command's output to your dotfiles (e.g. `~/.profile`, `~/.bash_profile`, or `~/.zprofile`)
+#:  with: `eval "$(/path/to/brew shellenv)"`.
+#:
+#:  The variable `HOMEBREW_SHELLENV_PREFIX` may be inherited from the parent shell session. If you explicitly
+#:  modified the path variables (e.g. `PATH`) in your dotfiles which breaks the subshell varibale inheritecement,
+#:  please use `eval "$(HOMEBREW_SHELLENV_PREFIX='' /path/to/brew shellenv)"` to always get all the export statements.
 
 # HOMEBREW_CELLAR and HOMEBREW_PREFIX are set by extend/ENV/super.rb
 # HOMEBREW_REPOSITORY is set by bin/brew
 # shellcheck disable=SC2154
 homebrew-shellenv() {
-  [[ "${HOMEBREW_SHELLENV_PREFIX}" == "${HOMEBREW_PREFIX}" ]] && return
+  if [[ "${HOMEBREW_SHELLENV_PREFIX}" == "${HOMEBREW_PREFIX}" ]]; then
+    [[ "$(PATH="${HOMEBREW_PATH}" command -v brew)" == "${HOMEBREW_PREFIX}/bin/brew" ]] && return
+    opoo "You have set HOMEBREW_SHELLENV_PREFIX=\"${HOMEBREW_SHELLENV_PREFIX}\"," \
+         "but the brew's executable does not present in your PATH." \
+         "Please run \`brew help shellenv\` for more information."
+  fi
 
   case "$(/bin/ps -p "${PPID}" -c -o comm=)" in
     fish | -fish)
diff --git a/docs/Manpage.md b/docs/Manpage.md
index 12b9f20c17..63a494ebb8 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -570,7 +570,13 @@ Print export statements. When run in a shell, this installation of Homebrew will
 
 The variables `HOMEBREW_PREFIX`, `HOMEBREW_CELLAR` and `HOMEBREW_REPOSITORY` are also exported to avoid querying them multiple times.
 The variable `HOMEBREW_SHELLENV_PREFIX` will be exported to avoid adding duplicate entries to the environment variables.
-Consider adding evaluation of this command's output to your dotfiles (e.g. `~/.profile`, `~/.bash_profile`, or `~/.zprofile`) with: `eval $(brew shellenv)`
+
+Consider adding evaluation of this command's output to your dotfiles (e.g. `~/.profile`, `~/.bash_profile`, or `~/.zprofile`)
+with: `eval "$(/path/to/brew shellenv)"`.
+
+The variable `HOMEBREW_SHELLENV_PREFIX` may be inherited from the parent shell session. If you explicitly
+modified the path variables (e.g. `PATH`) in your dotfiles which breaks the subshell varibale inheritecement,
+please use `eval "$(HOMEBREW_SHELLENV_PREFIX='' /path/to/brew shellenv)"` to always get all the export statements.
 
 ### `tap` [*`options`*] [*`user`*`/`*`repo`*] [*`URL`*]
 
diff --git a/manpages/brew.1 b/manpages/brew.1
index 3586e59ecf..9a16049cfc 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -792,7 +792,13 @@ Search for \fItext\fR in the given database\.
 Print export statements\. When run in a shell, this installation of Homebrew will be added to your \fBPATH\fR, \fBMANPATH\fR, and \fBINFOPATH\fR\.
 .
 .P
-The variables \fBHOMEBREW_PREFIX\fR, \fBHOMEBREW_CELLAR\fR and \fBHOMEBREW_REPOSITORY\fR are also exported to avoid querying them multiple times\. The variable \fBHOMEBREW_SHELLENV_PREFIX\fR will be exported to avoid adding duplicate entries to the environment variables\. Consider adding evaluation of this command\'s output to your dotfiles (e\.g\. \fB~/\.profile\fR, \fB~/\.bash_profile\fR, or \fB~/\.zprofile\fR) with: \fBeval $(brew shellenv)\fR
+The variables \fBHOMEBREW_PREFIX\fR, \fBHOMEBREW_CELLAR\fR and \fBHOMEBREW_REPOSITORY\fR are also exported to avoid querying them multiple times\. The variable \fBHOMEBREW_SHELLENV_PREFIX\fR will be exported to avoid adding duplicate entries to the environment variables\.
+.
+.P
+Consider adding evaluation of this command\'s output to your dotfiles (e\.g\. \fB~/\.profile\fR, \fB~/\.bash_profile\fR, or \fB~/\.zprofile\fR) with: \fBeval "$(/path/to/brew shellenv)"\fR\.
+.
+.P
+The variable \fBHOMEBREW_SHELLENV_PREFIX\fR may be inherited from the parent shell session\. If you explicitly modified the path variables (e\.g\. \fBPATH\fR) in your dotfiles which breaks the subshell varibale inheritecement, please use \fBeval "$(HOMEBREW_SHELLENV_PREFIX=\'\' /path/to/brew shellenv)"\fR to always get all the export statements\.
 .
 .SS "\fBtap\fR [\fIoptions\fR] [\fIuser\fR\fB/\fR\fIrepo\fR] [\fIURL\fR]"
 Tap a formula repository\.