diff --git a/tests/interactive.expect.rc b/tests/interactive.expect.rc
index eb014935d..abfa41c5a 100644
--- a/tests/interactive.expect.rc
+++ b/tests/interactive.expect.rc
@@ -128,6 +128,7 @@ proc expect_prompt {args} {
                 set prompt_action [subst -nocommands {
                     if {!\$matched(any)} {
                         log_debug "triggered unmatched action in expect_prompt"
+                        log_debug "expect buffer: [quote \$expect_out(buffer)]"
                         uplevel 1 {$arg}
                     }
                 }]