diff --git a/pkgs/tools/misc/esphome/default.nix b/pkgs/tools/misc/esphome/default.nix
index c9de8abea95d..aa4e36253ab2 100644
--- a/pkgs/tools/misc/esphome/default.nix
+++ b/pkgs/tools/misc/esphome/default.nix
@@ -21,6 +21,11 @@ python3.pkgs.buildPythonApplication rec {
     sha256 = "0bz6gkrvn7mwmjsqrazgpy9r64m5jj462v0izgvdymkx8bjd8mpi";
   };
 
+  patches = [
+    # fix missing write permissions on src files before modifing them
+   ./fix-src-permissions.patch
+  ];
+
   postPatch = ''
     # remove all version pinning (E.g tornado==5.1.1 -> tornado)
     sed -i -e "s/==[0-9.]*//" requirements.txt
diff --git a/pkgs/tools/misc/esphome/fix-src-permissions.patch b/pkgs/tools/misc/esphome/fix-src-permissions.patch
new file mode 100644
index 000000000000..5e92350105dd
--- /dev/null
+++ b/pkgs/tools/misc/esphome/fix-src-permissions.patch
@@ -0,0 +1,46 @@
+From f72c5035944065941daaa236b60664657c777726 Mon Sep 17 00:00:00 2001
+From: Martin Weinelt <hexa@darmstadt.ccc.de>
+Date: Wed, 23 Jun 2021 04:50:35 +0200
+Subject: [PATCH] Set u+w for copied src files before trying to overwrite them
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+We store esphome in the nix store, which results in its file permissions
+being 0444. Esphome, when compiling a firmware image, will copy these
+files from the nix store to a working directory. When updating between
+versions it will notice these files changed and try to copy the new
+version over, which would break, because the user had no write
+permissions on the files.
+
+❯ esphome compile 01e4ac.yml
+INFO Reading configuration 01e4ac.yml...
+INFO Detected timezone 'CET' with UTC offset 1 and daylight saving time from 27 March 02:00:00 to 30 October 03:00:00
+INFO Generating C++ source...
+ERROR Error copying file /nix/store/lmzrgl1arqfd98jcss4rsmmy6dbffddn-esphome-1.19.2/lib/python3.8/site-packages/esphome/components/api/api_connection.cpp to 01e4ac/src/esphome/components/api/api_connection.cpp: [Errno 13] Permission denied: '01e4ac/src/esphome/components/api/api_connection.cpp'
+
+To fix this we modify chmod to 0644 just before esphome tries a copy
+operation, which will fix permissions on existing working directories
+just in time.
+---
+ esphome/helpers.py | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/esphome/helpers.py b/esphome/helpers.py
+index ad7b8272..c456f4ff 100644
+--- a/esphome/helpers.py
++++ b/esphome/helpers.py
+@@ -228,6 +228,10 @@ def copy_file_if_changed(src: os.PathLike, dst: os.PathLike) -> None:
+     if file_compare(src, dst):
+         return
+     mkdir_p(os.path.dirname(dst))
++    try:
++        os.chmod(dst, 0o644)
++    except OSError:
++        pass
+     try:
+         shutil.copy(src, dst)
+     except OSError as err:
+-- 
+2.31.1
+