diff --git a/tests/impure-runner.lisp b/tests/impure-runner.lisp
index 15167eb88..1f171f364 100644
--- a/tests/impure-runner.lisp
+++ b/tests/impure-runner.lisp
@@ -23,6 +23,8 @@
   (setf *break-on-failure* break-on-failure
         *break-on-expected-failure* break-on-expected-failure
         *break-on-error* break-on-error)
+  (when *break-on-error*
+    (enable-debugger))
   (when interpret
     (setf *test-evaluator-mode* :interpret)
     (push :interpreter *features*))
diff --git a/tests/run-tests.lisp b/tests/run-tests.lisp
index bc47c00af..d5cca2f7e 100644
--- a/tests/run-tests.lisp
+++ b/tests/run-tests.lisp
@@ -457,6 +457,8 @@
       (setf *input-manifest*
             (if manifest (read manifest) :ignore))))
   (format t "// Running pure tests (~a)~%" test-fun)
+  (when *break-on-error*
+    (enable-debugger))
   (let ((*failures* nil)
         ;; in case somebody corrupts CL-USER's use list, of course
         (standard-use-list (package-use-list "CL-USER")))