diff --git a/CHANGES b/CHANGES
index bfc7e96f..87d340ee 100644
--- a/CHANGES
+++ b/CHANGES
@@ -8,6 +8,7 @@ SVN-HEAD
               Detect excessive recursion depth during expression eval (#2365)
               Return a string rather than NULL for unknown errors
               Skip non-file sysfs entries for speed
+              Fix memory leak in scanner when using flex 2.5.9 or later
   lm_sensors.init: Support new format of /etc/sysconfig/lm_sensors (#2246)
                    Drop support for kernels 2.4 and earlier
   lm_sensors.init.suse: Delete (actual SuSE script is much different)
diff --git a/lib/conf-lex.l b/lib/conf-lex.l
index afacefa7..0268f693 100644
--- a/lib/conf-lex.l
+++ b/lib/conf-lex.l
@@ -350,5 +350,15 @@ void sensors_scanner_exit(void)
 {
 	sensors_yy_delete_buffer(scan_buf);
 	scan_buf = (YY_BUFFER_STATE)0;
+
+/* As of flex 2.5.9, yylex_destroy() must be called when done with the
+   scaller, otherwise we'll leak memory. */
+#if defined(YY_FLEX_MAJOR_VERSION) && defined(YY_FLEX_MINOR_VERSION) && defined(YY_FLEX_SUBMINOR_VERSION)
+#if YY_FLEX_MAJOR_VERSION > 2 || \
+    (YY_FLEX_MAJOR_VERSION == 2 && (YY_FLEX_MINOR_VERSION > 5 || \
+				    (YY_FLEX_MINOR_VERSION == 5 && YY_FLEX_SUBMINOR_VERSION >= 9)))
+	sensors_yylex_destroy();
+#endif
+#endif
 }