diff --git a/pkgs/development/python-modules/fonttools/default.nix b/pkgs/development/python-modules/fonttools/default.nix
index b7f7b7e1326f..7fc9a62294a4 100644
--- a/pkgs/development/python-modules/fonttools/default.nix
+++ b/pkgs/development/python-modules/fonttools/default.nix
@@ -39,6 +39,12 @@ buildPythonPackage rec {
     hash = "sha256-ZkC1+I2d9wY9J7IoCGHGWG2gOVN7wW274UpN1lQxmJY=";
   };
 
+  patches = [
+    # https://github.com/fonttools/fonttools/pull/3855
+    # FIXME: remove when merged
+    ./python-3.13.4.patch
+  ];
+
   build-system = [
     setuptools
     setuptools-scm
diff --git a/pkgs/development/python-modules/fonttools/python-3.13.4.patch b/pkgs/development/python-modules/fonttools/python-3.13.4.patch
new file mode 100644
index 000000000000..c05def255b17
--- /dev/null
+++ b/pkgs/development/python-modules/fonttools/python-3.13.4.patch
@@ -0,0 +1,25 @@
+diff --git a/Lib/fontTools/feaLib/ast.py b/Lib/fontTools/feaLib/ast.py
+index efcce8c680..18e5a891d3 100644
+--- a/Lib/fontTools/feaLib/ast.py
++++ b/Lib/fontTools/feaLib/ast.py
+@@ -719,7 +719,8 @@ def __init__(self, prefix, glyphs, suffix, lookups, location=None):
+         for i, lookup in enumerate(lookups):
+             if lookup:
+                 try:
+-                    (_ for _ in lookup)
++                    for _ in lookup:
++                        break
+                 except TypeError:
+                     self.lookups[i] = [lookup]
+ 
+@@ -777,7 +778,8 @@ def __init__(self, prefix, glyphs, suffix, lookups, location=None):
+         for i, lookup in enumerate(lookups):
+             if lookup:
+                 try:
+-                    (_ for _ in lookup)
++                    for _ in lookup:
++                        break
+                 except TypeError:
+                     self.lookups[i] = [lookup]
+ 
+