diff --git a/ChangeLog b/ChangeLog
index b67aaea5..2d770347 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -25061,3 +25061,7 @@
 2025-10-13 Fred Gleason <fredg@paravelsystems.com>
 	* Incremented the package version to 4.4.1.
 	* Incremented the Python API version to 4.4.1.
+2025-10-23 Fred Gleason <fredg@paravelsystems.com>
+	* Fixed a bug in 'RDCart::updateLength()' that could cause patently
+	ridiculous values to be calculated for the 'Start' and 'End'
+	date-time columns in the cart library.
diff --git a/lib/rdescape_string.cpp b/lib/rdescape_string.cpp
index 613d2a3a..c431c6af 100644
--- a/lib/rdescape_string.cpp
+++ b/lib/rdescape_string.cpp
@@ -49,12 +49,17 @@ QString RDCheckDateTime(QTime const &time, QString const &format)
 QString RDCheckDateTime(QDateTime const &datetime, QString const &format)
 {
   QString checkedValue = "NULL";
+
+  if((datetime==RDCheckDateTime_InvalidStart)||
+     (datetime==RDCheckDateTime_InvalidEnd)) {
+    return checkedValue;
+  }
   
-  if(datetime.isValid())
+  if(datetime.isValid()) {
     checkedValue = "\"" + datetime.toString(format) + "\"";
-  
+  }
+
   return checkedValue;
-  
 }
 
 /**
diff --git a/lib/rdescape_string.h b/lib/rdescape_string.h
index a9b803d9..f3cf39af 100644
--- a/lib/rdescape_string.h
+++ b/lib/rdescape_string.h
@@ -25,6 +25,16 @@
 #include <qdatetime.h>
 #include <qstring.h>
 
+/*
+ * These are used in conjunction with the code in RDCart::updateLength()
+ * to calculate the outer limits of a disjunctive set of QDateTime values.
+ *
+ * If either of these values are found by RDCheckDateTime(), they will be
+ * returned as a NULL value (meaning, "no limits were found").
+ */
+#define RDCheckDateTime_InvalidStart QDateTime(QDate(3000,1,1),QTime(0,0,0))
+#define RDCheckDateTime_InvalidEnd QDateTime(QDate(1000,1,1),QTime(0,0,0))
+
 QString RDCheckDateTime(const QTime &time, const QString &format);
 QString RDCheckDateTime(const QDateTime &datetime, const QString &format);
 QString RDCheckDateTime(const QDate &date, const QString &format);