diff --git a/changes/bug19999_prep b/changes/bug19999_prep
index e8bb4a571b..769c870fe9 100644
--- a/changes/bug19999_prep
+++ b/changes/bug19999_prep
@@ -12,6 +12,8 @@
     - Our link-handshake unit tests now check, that when invalid
       handshakes fail, they fail with the error messages we
       expected.
+    - The unit tests now treat any failure of a "tor_assert_nonfatal()"
+      assertion as a test failure.
 
   o Minor bugfixes (unit tests):
     - The tor_tls_server_info_callback unit test no longer crashes when
diff --git a/src/common/util_bug.c b/src/common/util_bug.c
index f1cd33642e..08aba47974 100644
--- a/src/common/util_bug.c
+++ b/src/common/util_bug.c
@@ -14,6 +14,7 @@
 #include "container.h"
 
 #ifdef TOR_UNIT_TESTS
+static void (*failed_assertion_cb)(void) = NULL;
 static int n_bugs_to_capture = 0;
 static smartlist_t *bug_messages = NULL;
 #define capturing_bugs() (bug_messages != NULL && n_bugs_to_capture)
@@ -45,6 +46,15 @@ add_captured_bug(const char *s)
   --n_bugs_to_capture;
   smartlist_add(bug_messages, tor_strdup(s));
 }
+/** Set a callback to be invoked when we get any tor_bug_occurred_
+ * invocation. We use this in the unit tests so that a nonfatal
+ * assertion failure can also count as a test failure.
+ */
+void
+tor_set_failed_assertion_callback(void (*fn)(void))
+{
+  failed_assertion_cb = fn;
+}
 #else
 #define capturing_bugs() (0)
 #define add_captured_bug(s) do { } while (0)
@@ -95,5 +105,11 @@ tor_bug_occurred_(const char *fname, unsigned int line,
                  expr, func, fname, line);
   }
   log_backtrace(LOG_WARN, LD_BUG, buf);
+
+#ifdef TOR_UNIT_TESTS
+  if (failed_assertion_cb) {
+    failed_assertion_cb();
+  }
+#endif
 }
 
diff --git a/src/common/util_bug.h b/src/common/util_bug.h
index 049ca1a6ef..8b69a47607 100644
--- a/src/common/util_bug.h
+++ b/src/common/util_bug.h
@@ -153,6 +153,7 @@ void tor_bug_occurred_(const char *fname, unsigned int line,
 void tor_capture_bugs_(int n);
 void tor_end_capture_bugs_(void);
 const struct smartlist_t *tor_get_captured_bug_log_(void);
+void tor_set_failed_assertion_callback(void (*fn)(void));
 #endif
 
 #endif
diff --git a/src/test/testing_common.c b/src/test/testing_common.c
index 6460713f75..29f36a3da6 100644
--- a/src/test/testing_common.c
+++ b/src/test/testing_common.c
@@ -217,6 +217,12 @@ const struct testcase_setup_t passthrough_setup = {
   passthrough_test_setup, passthrough_test_cleanup
 };
 
+static void
+an_assertion_failed(void)
+{
+  tinytest_set_test_failed_();
+}
+
 /** Main entry point for unit test code: parse the command line, and run
  * some unit tests. */
 int
@@ -299,6 +305,7 @@ main(int c, const char **v)
     tor_free(errmsg);
     return 1;
   }
+  tor_set_failed_assertion_callback(an_assertion_failed);
 
   atexit(remove_directory);