diff --git a/src/NodaUncertaintyHelper.php b/src/NodaUncertaintyHelper.php
index aea223e..0014d4d 100644
--- a/src/NodaUncertaintyHelper.php
+++ b/src/NodaUncertaintyHelper.php
@@ -75,6 +75,8 @@ final class NodaUncertaintyHelper {
         "c. ",
         "ca ",
         "ca. ",
+        "Ca ",
+        "Ca. ",
         "za. ",
         "~",
         "circa ",