diff --git a/CHANGELOG.md b/CHANGELOG.md
index a35b7b2..895d984 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,8 +11,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Don't allow calling `zmodule` from the command line. Let it fail with "command
   not found" instead, as it's intended to be used only in the .zimrc script.
+- `ZIM_HOME` must be defined before sourcing zimfw.zsh. All documentation was
+  already doing so, hence not considering this is a breaking change.
 - Allow zimfw.zsh to exist anywhere else, not only inside `ZIM_HOME`. This
   enables installing the zimfw.zsh script independently with a package manager.
+- Don't try to upgrade if sourced zimfw.zsh is not in a writable path or is a
+  symlink.
 
 ### Fixed
 
@@ -148,7 +152,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   [here](https://github.com/zimfw/completion/blob/9386a76eac3f55b1c04d57d26238f725b4b3ba25/init.zsh#L10-L11).
 - Don't compile user Zsh startup scripts anymore
   (See [#450](https://github.com/zimfw/zimfw/pull/450)). This means you can:
-  - either manually delete the compiled files, as they won't be updated by Zim
+  - either manually delete the compiled files, as they won't be updated by zimfw
     anymore (recommended):
     ```
     for zfile in ${ZDOTDIR:-${HOME}}/.z(shenv|profile|shrc|login|logout); do
@@ -349,7 +353,7 @@ Take your time to review the updated [README.md] and the changes listed below.
 - The Zim "core" is reduced to a single file, namely zimfw.zsh, that is
   self-updated without requiring git. With this, `ZIM_HOME` is not (the root of)
   a git repo anymore.
-- Zsh and modules are configured in .zshrc instead of .zimrc.
+- Zsh and modules are initialized in .zshrc instead of .zimrc.
 - .zimrc is not sourced during Zsh startup anymore, and only contains the module
   definitions.
 - Zim's init.zsh and login_init.zsh scripts are generated by the `zimfw` CLI
@@ -388,7 +392,8 @@ Take your time to review the updated [README.md] and the changes listed below.
 [termtitle]: https://github.com/zimfw/termtitle
 [s1ck94]: https://github.com/zimfw/s1ck94
 
-[Unreleased]: https://github.com/zimfw/zimfw/compare/v1.13.0...HEAD
+[Unreleased]: https://github.com/zimfw/zimfw/compare/v1.13.1...HEAD
+[1.13.1]: https://github.com/zimfw/zimfw/compare/v1.13.0...v1.13.1
 [1.13.0]: https://github.com/zimfw/zimfw/compare/v1.12.1...v1.13.0
 [1.12.1]: https://github.com/zimfw/zimfw/compare/v1.12.0...v1.12.1
 [1.12.0]: https://github.com/zimfw/zimfw/compare/v1.11.3...v1.12.0
diff --git a/src/stage2/50_zimfw_upgrade.zsh.erb b/src/stage2/50_zimfw_upgrade.zsh.erb
index d7f8cbc..901ef14 100644
--- a/src/stage2/50_zimfw_upgrade.zsh.erb
+++ b/src/stage2/50_zimfw_upgrade.zsh.erb
@@ -1,5 +1,13 @@
 _zimfw_upgrade() {
+  if [[ ! -w ${__ZIMFW_PATH} ]]; then
+    print -u2 -R $'<%= red %>No write access to <%= bold %>'${__ZIMFW_PATH}$'<%= normalred %>. Will not try to upgrade.<%= normal %>'
+    return 1
+  fi
   local -r ztarget=${__ZIMFW_PATH}/zimfw.zsh zurl=https://github.com/zimfw/zimfw/releases/latest/download/zimfw.zsh.gz
+  if [[ -L ${ztarget} || ! -f ${ztarget} ]]; then
+    print -u2 -R $'<%= red %><%= bold %>'${ztarget}$'<%= normalred %> is a symlink or not a regular file. Will not try to upgrade.<%= normal %>'
+    return 1
+  fi
   {
     if (( ${+commands[curl]} )); then
       command curl -fsSL -o ${ztarget}.new.gz ${zurl} || return 1
diff --git a/zimfw.zsh b/zimfw.zsh
index a6aec57..3694438 100644
--- a/zimfw.zsh
+++ b/zimfw.zsh
@@ -462,7 +462,7 @@ _zimfw_compile() {
 }
 
 _zimfw_info() {
-  print -R 'zimfw version:        '${_zversion}' (built at 2024-06-17 12:21:22 UTC, previous commit is 76164d6)'
+  print -R 'zimfw version:        '${_zversion}' (built at 2024-06-18 22:08:02 UTC, previous commit is 897afc9)'
   local zparam
   for zparam in LANG ${(Mk)parameters:#LC_*} OSTYPE TERM TERM_PROGRAM TERM_PROGRAM_VERSION ZIM_HOME ZSH_VERSION; do
     print -R ${(r.22....:.)zparam}${(P)zparam}
@@ -482,7 +482,15 @@ _zimfw_uninstall() {
 }
 
 _zimfw_upgrade() {
+  if [[ ! -w ${__ZIMFW_PATH} ]]; then
+    print -u2 -R $'\E[31mNo write access to \E[1m'${__ZIMFW_PATH}$'\E[0;31m. Will not try to upgrade.\E[0m'
+    return 1
+  fi
   local -r ztarget=${__ZIMFW_PATH}/zimfw.zsh zurl=https://github.com/zimfw/zimfw/releases/latest/download/zimfw.zsh.gz
+  if [[ -L ${ztarget} || ! -f ${ztarget} ]]; then
+    print -u2 -R $'\E[31m\E[1m'${ztarget}$'\E[0;31m is a symlink or not a regular file. Will not try to upgrade.\E[0m'
+    return 1
+  fi
   {
     if (( ${+commands[curl]} )); then
       command curl -fsSL -o ${ztarget}.new.gz ${zurl} || return 1