diff --git a/pkgs/applications/science/math/sage/patches/disable-pexpect-intermittent-failure.patch b/pkgs/applications/science/math/sage/patches/disable-pexpect-intermittent-failure.patch
new file mode 100644
index 000000000000..374c72079194
--- /dev/null
+++ b/pkgs/applications/science/math/sage/patches/disable-pexpect-intermittent-failure.patch
@@ -0,0 +1,29 @@
+diff --git a/src/sage/interfaces/singular.py b/src/sage/interfaces/singular.py
+index 88a33b0349..b3321f0bec 100644
+--- a/src/sage/interfaces/singular.py
++++ b/src/sage/interfaces/singular.py
+@@ -495,24 +495,6 @@ class Singular(ExtraTabCompletion, Expect):
+         """
+         Send an interrupt to Singular. If needed, additional
+         semi-colons are sent until we get back at the prompt.
+-
+-        TESTS:
+-
+-        The following works without restarting Singular::
+-
+-            sage: a = singular(1)
+-            sage: _ = singular._expect.sendline('1+')  # unfinished input
+-            sage: try:
+-            ....:     alarm(0.5)
+-            ....:     singular._expect_expr('>')  # interrupt this
+-            ....: except KeyboardInterrupt:
+-            ....:     pass
+-            Control-C pressed.  Interrupting Singular. Please wait a few seconds...
+-
+-        We can still access a::
+-
+-            sage: 2*a
+-            2
+         """
+         # Work around for Singular bug
+         # http://www.singular.uni-kl.de:8002/trac/ticket/727
diff --git a/pkgs/applications/science/math/sage/patches/dont-grep-threejs-version-from-minified-js.patch b/pkgs/applications/science/math/sage/patches/dont-grep-threejs-version-from-minified-js.patch
new file mode 100644
index 000000000000..88cb66506b1d
--- /dev/null
+++ b/pkgs/applications/science/math/sage/patches/dont-grep-threejs-version-from-minified-js.patch
@@ -0,0 +1,16 @@
+diff --git a/src/sage/repl/rich_output/display_manager.py b/src/sage/repl/rich_output/display_manager.py
+index fb21f7a9c9..f39470777d 100644
+--- a/src/sage/repl/rich_output/display_manager.py
++++ b/src/sage/repl/rich_output/display_manager.py
+@@ -749,9 +749,9 @@ class DisplayManager(SageObject):
+             import sage.env
+             import re
+             import os
+-            with open(os.path.join(sage.env.THREEJS_DIR, 'build', 'three.min.js')) as f:
++            with open(os.path.join(sage.env.THREEJS_DIR, 'build', 'three.js')) as f:
+                 text = f.read().replace('\n','')
+-            version = re.search(r'REVISION="(\d+)"', text).group(1)
++            version = re.search(r"REVISION = '(\d+)'", text).group(1)
+             return """
+ <script src="https://cdn.jsdelivr.net/gh/mrdoob/three.js@r{0}/build/three.min.js"></script>
+ <script src="https://cdn.jsdelivr.net/gh/mrdoob/three.js@r{0}/examples/js/controls/OrbitControls.js"></script>
diff --git a/pkgs/applications/science/math/sage/sage-src.nix b/pkgs/applications/science/math/sage/sage-src.nix
index b8fb41596607..ff8e53d4172c 100644
--- a/pkgs/applications/science/math/sage/sage-src.nix
+++ b/pkgs/applications/science/math/sage/sage-src.nix
@@ -71,6 +71,9 @@ stdenv.mkDerivation rec {
 
     # fix intermittent errors in sagespawn.pyx: https://trac.sagemath.org/ticket/31052
     ./patches/sagespawn-implicit-casting.patch
+
+    # disable pexpect interrupt test (see https://trac.sagemath.org/ticket/30945)
+    ./patches/disable-pexpect-intermittent-failure.patch
   ];
 
   # Patches needed because of package updates. We could just pin the versions of
@@ -106,6 +109,9 @@ stdenv.mkDerivation rec {
 
     # fix test output with sympy 1.7 (https://trac.sagemath.org/ticket/30985)
     ./patches/sympy-1.7-update.patch
+
+    # workaround until we use sage's fork of threejs, which contains a "version" file
+    ./patches/dont-grep-threejs-version-from-minified-js.patch
   ];
 
   patches = nixPatches ++ bugfixPatches ++ packageUpgradePatches;