diff --git a/src/NodaUncertaintyHelper.php b/src/NodaUncertaintyHelper.php
index 48f090b..12d7fab 100644
--- a/src/NodaUncertaintyHelper.php
+++ b/src/NodaUncertaintyHelper.php
@@ -150,6 +150,7 @@ final class NodaUncertaintyHelper {
     public const TIME_UNCERTAINTY_SUFFIXES = [
         "(?)",
         "?",
+        " ca.",
         " (ca.)",
         " [ca.]",
         " (circa)",