diff --git a/common/lib/capa/capa/capa_problem.py b/common/lib/capa/capa/capa_problem.py
index 209c7ddd50..90a336bde0 100644
--- a/common/lib/capa/capa/capa_problem.py
+++ b/common/lib/capa/capa/capa_problem.py
@@ -71,7 +71,11 @@ class LoncapaSystem(object):
     can provide these resources however make sense for their environment, and
     this code can remain independent.
 
-    See :class:`ModuleSystem` for documentation of these attributes.
+    Attributes:
+        i18n: an object implementing the `gettext.Translations` interface so
+            that we can use `.ugettext` to localize strings.
+
+    See :class:`ModuleSystem` for documentation of other attributes.
 
     """
     def __init__(                                       # pylint: disable=invalid-name
@@ -82,6 +86,7 @@ class LoncapaSystem(object):
         can_execute_unsafe_code,
         DEBUG,                                          # pylint: disable=invalid-name
         filestore,
+        i18n,
         node_path,
         render_template,
         seed,      # Why do we do this if we have self.seed?
@@ -94,6 +99,7 @@ class LoncapaSystem(object):
         self.can_execute_unsafe_code = can_execute_unsafe_code
         self.DEBUG = DEBUG                              # pylint: disable=invalid-name
         self.filestore = filestore
+        self.i18n = i18n
         self.node_path = node_path
         self.render_template = render_template
         self.seed = seed                     # Why do we do this if we have self.seed?
diff --git a/common/lib/capa/capa/responsetypes.py b/common/lib/capa/capa/responsetypes.py
index 5db1f61920..ed7b4bfddd 100644
--- a/common/lib/capa/capa/responsetypes.py
+++ b/common/lib/capa/capa/responsetypes.py
@@ -875,8 +875,9 @@ class NumericalResponse(LoncapaResponse):
                 correct_ans = evaluator({}, {}, self.correct_answer)
             except Exception:
                 log.debug("Content error--answer '%s' is not a valid number", self.correct_answer)
+                _ = self.capa_system.i18n.ugettext
                 raise StudentInputError(
-                    "There was a problem with the staff answer to this problem"
+                    _("There was a problem with the staff answer to this problem")
                 )
 
         return correct_ans
diff --git a/common/lib/capa/capa/tests/__init__.py b/common/lib/capa/capa/tests/__init__.py
index db0af9cc8a..d5d3f87f81 100644
--- a/common/lib/capa/capa/tests/__init__.py
+++ b/common/lib/capa/capa/tests/__init__.py
@@ -1,5 +1,6 @@
 """Tools for helping with testing capa."""
 
+import gettext
 import os
 import os.path
 
@@ -41,6 +42,7 @@ def test_capa_system():
         can_execute_unsafe_code=lambda: False,
         DEBUG=True,
         filestore=fs.osfs.OSFS(os.path.join(TEST_DIR, "test_files")),
+        i18n=gettext.NullTranslations(),
         node_path=os.environ.get("NODE_PATH", "/usr/local/lib/node_modules"),
         render_template=tst_render_template,
         seed=0,
diff --git a/common/lib/capa/capa/tests/test_responsetypes.py b/common/lib/capa/capa/tests/test_responsetypes.py
index ebf985ceed..d614ac9d27 100644
--- a/common/lib/capa/capa/tests/test_responsetypes.py
+++ b/common/lib/capa/capa/tests/test_responsetypes.py
@@ -1140,6 +1140,24 @@ class NumericalResponseTest(ResponseTest):
             "Content error--answer '%s' is not a valid number", staff_ans
         )
 
+    @mock.patch('capa.responsetypes.log')
+    def test_responsetype_i18n(self, mock_log):
+        """Test that LoncapaSystem has an i18n that works."""
+        staff_ans = "clearly bad syntax )[+1e"
+        problem = self.build_problem(answer=staff_ans, tolerance=1e-3)
+
+        class FakeTranslations(object):
+            """A fake gettext.Translations object."""
+            def ugettext(self, text):
+                """Return the 'translation' of `text`."""
+                if text == "There was a problem with the staff answer to this problem":
+                    text = "TRANSLATED!"
+                return text
+        problem.capa_system.i18n = FakeTranslations()
+
+        with self.assertRaisesRegexp(StudentInputError, "TRANSLATED!"):
+            self.assert_grade(problem, '1+j', 'correct')
+
     def test_grade_infinity(self):
         """
         Check that infinity doesn't automatically get marked correct.
diff --git a/common/lib/xmodule/xmodule/capa_base.py b/common/lib/xmodule/xmodule/capa_base.py
index 7091d4e45f..1475bae4b0 100644
--- a/common/lib/xmodule/xmodule/capa_base.py
+++ b/common/lib/xmodule/xmodule/capa_base.py
@@ -267,6 +267,7 @@ class CapaMixin(CapaFields):
             can_execute_unsafe_code=self.system.can_execute_unsafe_code,
             DEBUG=self.system.DEBUG,
             filestore=self.system.filestore,
+            i18n=self.system.service(self, "i18n"),
             node_path=self.system.node_path,
             render_template=self.system.render_template,
             seed=self.system.seed,      # Why do we do this if we have self.seed?