diff --git a/CHANGES b/CHANGES
index f682cc3c9d..da0a5b0d51 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,5 @@
+  89.   [cleanup]       <isc/lex.h> does not need <stddef.h>.
+
   88.   [cleanup]       <isc/interfaceiter.h> does not need <isc/result.h> or
                         <isc/mem.h>.  isc_interface_t and isc_interfaceiter_t
                         moved to <isc/types.h>.
diff --git a/lib/isc/include/isc/lex.h b/lib/isc/include/isc/lex.h
index ef26443692..dae5f96dd0 100644
--- a/lib/isc/include/isc/lex.h
+++ b/lib/isc/include/isc/lex.h
@@ -52,7 +52,6 @@
  ***/
 
 #include <stdio.h>
-#include <stddef.h>
 
 #include <isc/lang.h>
 #include <isc/region.h>