diff --git a/Library/Homebrew/brew.sh b/Library/Homebrew/brew.sh
index 558f818a55..d950b9f8c3 100644
--- a/Library/Homebrew/brew.sh
+++ b/Library/Homebrew/brew.sh
@@ -348,31 +348,38 @@ export USER="${USER:-$(id -un)}"
 # Higher depths mean this command was invoked by another Homebrew command.
 export HOMEBREW_COMMAND_DEPTH="$((HOMEBREW_COMMAND_DEPTH + 1))"
 
-# This is set by the user environment.
-# shellcheck disable=SC2154
-if [[ -n "${HOMEBREW_FORCE_BREWED_CURL}" && -x "${HOMEBREW_PREFIX}/opt/curl/bin/curl" ]] &&
-   "${HOMEBREW_PREFIX}/opt/curl/bin/curl" --version &>/dev/null
-then
-  HOMEBREW_CURL="${HOMEBREW_PREFIX}/opt/curl/bin/curl"
-elif [[ -n "${HOMEBREW_DEVELOPER}" && -x "${HOMEBREW_CURL_PATH}" ]]
-then
-  HOMEBREW_CURL="${HOMEBREW_CURL_PATH}"
-else
-  HOMEBREW_CURL="curl"
-fi
+setup_curl() {
+  # This is set by the user environment.
+  # shellcheck disable=SC2154
+  if [[ -n "${HOMEBREW_FORCE_BREWED_CURL}" && -x "${HOMEBREW_PREFIX}/opt/curl/bin/curl" ]] &&
+     "${HOMEBREW_PREFIX}/opt/curl/bin/curl" --version &>/dev/null
+  then
+    HOMEBREW_CURL="${HOMEBREW_PREFIX}/opt/curl/bin/curl"
+  elif [[ -n "${HOMEBREW_DEVELOPER}" && -x "${HOMEBREW_CURL_PATH}" ]]
+  then
+    HOMEBREW_CURL="${HOMEBREW_CURL_PATH}"
+  else
+    HOMEBREW_CURL="curl"
+  fi
+}
 
-# This is set by the user environment.
-# shellcheck disable=SC2154
-if [[ -n "${HOMEBREW_FORCE_BREWED_GIT}" && -x "${HOMEBREW_PREFIX}/opt/git/bin/git" ]] &&
-   "${HOMEBREW_PREFIX}/opt/git/bin/git" --version &>/dev/null
-then
-  HOMEBREW_GIT="${HOMEBREW_PREFIX}/opt/git/bin/git"
-elif [[ -n "${HOMEBREW_DEVELOPER}" && -x "${HOMEBREW_GIT_PATH}" ]]
-then
-  HOMEBREW_GIT="${HOMEBREW_GIT_PATH}"
-else
-  HOMEBREW_GIT="git"
-fi
+setup_git() {
+  # This is set by the user environment.
+  # shellcheck disable=SC2154
+  if [[ -n "${HOMEBREW_FORCE_BREWED_GIT}" && -x "${HOMEBREW_PREFIX}/opt/git/bin/git" ]] &&
+     "${HOMEBREW_PREFIX}/opt/git/bin/git" --version &>/dev/null
+  then
+    HOMEBREW_GIT="${HOMEBREW_PREFIX}/opt/git/bin/git"
+  elif [[ -n "${HOMEBREW_DEVELOPER}" && -x "${HOMEBREW_GIT_PATH}" ]]
+  then
+    HOMEBREW_GIT="${HOMEBREW_GIT_PATH}"
+  else
+    HOMEBREW_GIT="git"
+  fi
+}
+
+setup_curl
+setup_git
 
 HOMEBREW_VERSION="$("${HOMEBREW_GIT}" -C "${HOMEBREW_REPOSITORY}" describe --tags --dirty --abbrev=7 2>/dev/null)"
 HOMEBREW_USER_AGENT_VERSION="${HOMEBREW_VERSION}"
@@ -548,11 +555,18 @@ Your Git executable: $(unset git && type -p ${HOMEBREW_GIT})"
   fi
 fi
 
-if [[ -n "${HOMEBREW_FORCE_BREWED_CA_CERTIFICATES}" && -f "${HOMEBREW_PREFIX}/etc/ca-certificates/cert.pem" ]]
-then
-  export SSL_CERT_FILE="${HOMEBREW_PREFIX}/etc/ca-certificates/cert.pem"
-  export GIT_SSL_CAINFO="${HOMEBREW_PREFIX}/etc/ca-certificates/cert.pem"
-fi
+setup_ca_certificates() {
+  if [[ -n "${HOMEBREW_FORCE_BREWED_CA_CERTIFICATES}" && -f "${HOMEBREW_PREFIX}/etc/ca-certificates/cert.pem" ]]
+  then
+    export SSL_CERT_FILE="${HOMEBREW_PREFIX}/etc/ca-certificates/cert.pem"
+    export GIT_SSL_CAINFO="${HOMEBREW_PREFIX}/etc/ca-certificates/cert.pem"
+  fi
+}
+setup_ca_certificates
+
+# Redetermine curl and git paths as we may have forced some options above.
+setup_curl
+setup_git
 
 # A bug in the auto-update process prior to 3.1.2 means $HOMEBREW_BOTTLE_DOMAIN
 # could be passed down with the default domain.
diff --git a/Library/Homebrew/cmd/update.sh b/Library/Homebrew/cmd/update.sh
index 389871816c..a42bf47a97 100644
--- a/Library/Homebrew/cmd/update.sh
+++ b/Library/Homebrew/cmd/update.sh
@@ -390,6 +390,7 @@ EOS
     if [[ -d "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core" || -n "${HOMEBREW_INSTALL_FROM_API}" ]]
     then
       brew install ca-certificates
+      setup_ca_certificates
     fi
   fi
 
@@ -401,6 +402,8 @@ EOS
     then
       odie "'curl' must be installed and in your PATH!"
     fi
+
+    setup_curl
   fi
 
   if ! git --version &>/dev/null ||
@@ -411,6 +414,8 @@ EOS
     then
       odie "'git' must be installed and in your PATH!"
     fi
+
+    setup_git
   fi
 
   [[ -f "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core/.git/shallow" ]] && HOMEBREW_CORE_SHALLOW=1