diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3d98c18b9ba244574b14541f4c1fefbdc965f6c5..956ebb97b18040c87be62149560416b1ab9a5d41 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -26,12 +26,11 @@ Python 3.6 POCL:
 
 Python 3.5 Conda:
   script:
-  - export SUMPY_NO_CACHE=1
+  - export SUMPY_FORCE_SYMBOLIC_BACKEND=symengine
   - CONDA_ENVIRONMENT=.test-conda-env-py3.yml
   - REQUIREMENTS_TXT=.test-conda-env-py3-requirements.txt
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project-within-miniconda.sh
   - ". ./build-and-test-py-project-within-miniconda.sh"
-  allow_failure: true  # takes very long
   tags:
   - linux
   except:
diff --git a/.test-conda-env-py3.yml b/.test-conda-env-py3.yml
index 0ffd2f227f4b04395ab6ff09af01df366537aa35..75ea05f3d7608eb831754cf532b5dd3a62e8b6b0 100644
--- a/.test-conda-env-py3.yml
+++ b/.test-conda-env-py3.yml
@@ -1,7 +1,6 @@
 name: test-conda-env-py3
 channels:
 - inducer
-- symengine
 - conda-forge
 - defaults
 dependencies:
@@ -12,5 +11,6 @@ dependencies:
 - islpy
 - pyopencl
 - python=3.5
+- symengine=0.3.0
 - python-symengine=0.3.0
 # things not in here: loopy boxtree pymbolic pyfmmlib meshmode sumpy
diff --git a/test/test_matrix.py b/test/test_matrix.py
index cd70c0e3eeae3a205db2cba8778c8e91ff2c6634..f626a024a99589d6816514323ac5ea8051d759a9 100644
--- a/test/test_matrix.py
+++ b/test/test_matrix.py
@@ -25,17 +25,20 @@ THE SOFTWARE.
 import numpy as np
 import numpy.linalg as la
 import pyopencl as cl
+import pytest
 from meshmode.mesh.generation import (  # noqa
         ellipse, cloverleaf, starfish, drop, n_gon, qbx_peanut,
         make_curve_mesh)
 from pytential import bind, sym
 from functools import partial
+from sumpy.symbolic import USE_SYMENGINE
 
 from pyopencl.tools import (  # noqa
         pytest_generate_tests_for_pyopencl
         as pytest_generate_tests)
 
 
+@pytest.mark.skipif(USE_SYMENGINE, reason="line taylor in SymEngine is broken")
 def test_matrix_build(ctx_factory):
     cl_ctx = ctx_factory()
     queue = cl.CommandQueue(cl_ctx)