diff --git a/pkgs/applications/science/math/sage/sage-src.nix b/pkgs/applications/science/math/sage/sage-src.nix
index bc17147c16a7..619d24ce9ac3 100644
--- a/pkgs/applications/science/math/sage/sage-src.nix
+++ b/pkgs/applications/science/math/sage/sage-src.nix
@@ -151,6 +151,13 @@ stdenv.mkDerivation rec {
       url = "https://git.sagemath.org/sage.git/patch/?id=e351bf2f2914e683d5e2028597c45ae8d1b7f855";
       sha256 = "00faa7fl0vaqcqbw0bidkhl78qa8l34d3a07zirbcl0vm74bdn1p";
     })
+
+    # https://trac.sagemath.org/ticket/27653
+    (fetchpatch {
+      name = "sympy-1.4.patch";
+      url = "https://git.sagemath.org/sage.git/patch/?h=3277ba76d0ba7174608a31a0c6623e9210c63e3d";
+      sha256 = "09avaanwmdgqv14mmllbgw9z2scf4lc0y0kzdhlriiq8ss9j8iir";
+    })
   ];
 
   patches = nixPatches ++ bugfixPatches ++ packageUpgradePatches;
diff --git a/pkgs/development/python-modules/sympy/default.nix b/pkgs/development/python-modules/sympy/default.nix
index 1bf7511d2bb9..c09267662c17 100644
--- a/pkgs/development/python-modules/sympy/default.nix
+++ b/pkgs/development/python-modules/sympy/default.nix
@@ -8,25 +8,25 @@
 
 buildPythonPackage rec {
   pname = "sympy";
-  version = "1.3"; # Upgrades may break sage. Please test or ping @timokau.
+  version = "1.4"; # Upgrades may break sage. Please test or ping @timokau.
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "0m0vhyv15zszn19mk5xq3py4iijjbr7f3fpy1s57b8q7c9arncg1";
+    sha256 = "1q937csy8rd18pk2fz1ssj7jyj7l3rjx4nzbiz5vcymfhrb1x8bi";
   };
 
   checkInputs = [ glibcLocales ];
 
   propagatedBuildInputs = [ mpmath ];
 
-  # some tests fail: https://github.com/sympy/sympy/issues/15149
+  # tests take ~1h
   doCheck = false;
 
   patches = [
     # to be fixed by https://github.com/sympy/sympy/pull/13476
     (fetchpatch {
-      url = "https://git.sagemath.org/sage.git/plain/build/pkgs/sympy/patches/03_undeffun_sage.patch?id=07d6c37d18811e2b377a9689790a7c5e24da16ba";
-      sha256 = "1mh2va1rlgizgvx8yzqwgvbf5wvswarn511002b361mc8yy0bnhr";
+      url = "https://git.sagemath.org/sage.git/plain/build/pkgs/sympy/patches/03_undeffun_sage.patch?id=3277ba76d0ba7174608a31a0c6623e9210c63e3d";
+      sha256 = "0xcp1qafvqnivvvi0byh51mbgqicjhmswwvqvamjz9rxfzm5f7d7";
     })
   ];