diff --git a/tests/support/test.tcl b/tests/support/test.tcl
index 298e4c77932a06b2ff2639c14b084c697a6edcfd..93f64928e11b234092ed6bbab33a1c85f9a7b6ef 100644
--- a/tests/support/test.tcl
+++ b/tests/support/test.tcl
@@ -36,8 +36,8 @@ proc assert_encoding {enc key} {
     # Swapped out values don't have an encoding, so make sure that
     # the value is swapped in before checking the encoding.
     set dbg [r debug object $key]
-    while {[string match "* swapped:*" $dbg]} {
-        [r debug swapin $key]
+    while {[string match "* swapped at:*" $dbg]} {
+        r debug swapin $key
         set dbg [r debug object $key]
     }
     assert_match "* encoding:$enc *" $dbg