diff --git a/export.sh b/export.sh
index 0408a76bb..2ff8ee18e 100644
--- a/export.sh
+++ b/export.sh
@@ -1,6 +1,6 @@
 # This script should be sourced, not executed.
 
-function realpath_int() {
+realpath_int() {
     wdir="$PWD"; [ "$PWD" = "/" ] && wdir=""
     arg=$1
     case "$arg" in
@@ -12,44 +12,82 @@ function realpath_int() {
 }
 
 
-function idf_export_main() {
+idf_export_main() {
     # The file doesn't have executable permissions, so this shouldn't really happen.
     # Doing this in case someone tries to chmod +x it and execute...
-    if [[ -n "${BASH_SOURCE}" && ( "${BASH_SOURCE[0]}" == "${0}" ) ]]; then
+
+    # shellcheck disable=SC2128,SC2169,SC2039 # ignore array expansion warning
+    if [ -n "${BASH_SOURCE}" ] && [ "${BASH_SOURCE[0]}" = "${0}" ]
+    then
         echo "This script should be sourced, not executed:"
+        # shellcheck disable=SC2039  # reachable only with bash
         echo ". ${BASH_SOURCE[0]}"
         return 1
     fi
 
-    if [[ -z "${IDF_PATH}" ]]
+    if [ -z "${IDF_PATH}" ]
     then
-        # If using bash, try to guess IDF_PATH from script location
-        if [[ -n "${BASH_SOURCE}" ]]
+        # IDF_PATH not set in the environment.
+        # If using bash or zsh, try to guess IDF_PATH from script location.
+        self_path=""
+
+        # shellcheck disable=SC2128  # ignore array expansion warning
+        if [ -n "${BASH_SOURCE}" ]
         then
-            if [[ "$OSTYPE" == "darwin"* ]]; then
-                script_dir="$(realpath_int $BASH_SOURCE)"
-            else
-                script_name="$(readlink -f $BASH_SOURCE)"
-                script_dir="$(dirname $script_name)"
-            fi
-            export IDF_PATH="${script_dir}"
+            self_path="${BASH_SOURCE}"
+        elif [ -n "${ZSH_VERSION}" ]
+        then
+            self_path="${(%):-%x}"
         else
-            echo "IDF_PATH must be set before sourcing this script"
+            echo "Could not detect IDF_PATH. Please set it before sourcing this script:"
+            echo "  export IDF_PATH=(add path here)"
             return 1
         fi
+
+        # shellcheck disable=SC2169,SC2169,SC2039  # unreachable with 'dash'
+        if [[ "$OSTYPE" == "darwin"* ]]; then
+            # convert possibly relative path to absolute
+            script_dir="$(realpath_int "${self_path}")"
+            # resolve any ../ references to make the path shorter
+            script_dir="$(cd "${script_dir}" || exit 1; pwd)"
+        else
+            # convert to full path and get the directory name of that
+            script_name="$(readlink -f "${self_path}")"
+            script_dir="$(dirname "${script_name}")"
+        fi
+        export IDF_PATH="${script_dir}"
+        echo "Setting IDF_PATH to '${IDF_PATH}'"
+    else
+        # IDF_PATH came from the environment, check if the path is valid
+        if [ ! -d "${IDF_PATH}" ]
+        then
+            echo "IDF_PATH is set to '${IDF_PATH}', but it is not a valid directory."
+            echo "If you have set IDF_PATH manually, check if the path is correct."
+            return 1
+        fi
+        # Check if this path looks like an IDF directory
+        if [ ! -f "${IDF_PATH}/tools/idf.py" ] || [ ! -f "${IDF_PATH}/tools/idf_tools.py" ]
+        then
+            echo "IDF_PATH is set to '${IDF_PATH}', but it doesn't look like an ESP-IDF directory."
+            echo "If you have set IDF_PATH manually, check if the path is correct."
+            return 1
+        fi
+
+        # The varible might have been set (rather than exported), re-export it to be sure
+        export IDF_PATH="${IDF_PATH}"
     fi
 
-    old_path=$PATH
+    old_path="$PATH"
 
     echo "Adding ESP-IDF tools to PATH..."
     # Call idf_tools.py to export tool paths
     export IDF_TOOLS_EXPORT_CMD=${IDF_PATH}/export.sh
     export IDF_TOOLS_INSTALL_CMD=${IDF_PATH}/install.sh
-    idf_exports=$(${IDF_PATH}/tools/idf_tools.py export) || return 1
+    idf_exports=$("${IDF_PATH}/tools/idf_tools.py" export) || return 1
     eval "${idf_exports}"
 
     echo "Checking if Python packages are up to date..."
-    python ${IDF_PATH}/tools/check_python_dependencies.py || return 1
+    python "${IDF_PATH}/tools/check_python_dependencies.py" || return 1
 
 
     # Allow calling some IDF python tools without specifying the full path
@@ -59,9 +97,10 @@ function idf_export_main() {
     IDF_ADD_PATHS_EXTRAS="${IDF_ADD_PATHS_EXTRAS}:${IDF_PATH}/components/partition_table/"
     export PATH="${IDF_ADD_PATHS_EXTRAS}:${PATH}"
 
-    if [[ -n "$BASH" ]]
+    if [ -n "$BASH" ]
     then
         path_prefix=${PATH%%${old_path}}
+        # shellcheck disable=SC2169,SC2039  # unreachable with 'dash'
         paths="${path_prefix//:/ }"
         if [ -n "${paths}" ]; then
             echo "Added the following directories to PATH:"