diff --git a/src/NodaUncertaintyHelper.php b/src/NodaUncertaintyHelper.php
index 29d1c6b..7dffcfc 100644
--- a/src/NodaUncertaintyHelper.php
+++ b/src/NodaUncertaintyHelper.php
@@ -60,6 +60,7 @@ final class NodaUncertaintyHelper {
         "circa ",
         "ca. ",
         "ca ",
+        "c. ",
     ];
 
     const TIME_UNCERTAINTY_SUFFIXES = [