diff --git a/pytests/helpers/timeline.py b/pytests/helpers/timeline.py
index 10057034..819620b9 100644
--- a/pytests/helpers/timeline.py
+++ b/pytests/helpers/timeline.py
@@ -190,9 +190,23 @@ class Timeline(object):
             # First time wait_until() calls us, we have to check the whole timeline.
             # On subsequent calls, we only need to check the newly added occurrence.
             if check_past:
+                if explain:
+                    print(
+                        colors.LIGHT_MAGENTA + 'Testing ' + colors.RESET +
+                        colors.color_repr(expectation) +
+                        colors.LIGHT_MAGENTA + ' against timeline up to and including ' + colors.RESET +
+                        colors.color_repr(self.last)
+                    )
                 reasons.update(expectation.test_at_or_before(self.last) or {})
                 del check_past[:]
             else:
+                if explain:
+                    print(
+                        colors.LIGHT_MAGENTA + 'Testing ' + colors.RESET +
+                        colors.color_repr(expectation) +
+                        colors.LIGHT_MAGENTA + ' against ' + colors.RESET +
+                        colors.color_repr(self.last)
+                    )
                 reasons.update(expectation.test_at(self.last) or {})
 
             if reasons: