diff -up Python-3.9.0/Modules/_gdbmmodule.c.17~ Python-3.9.0/Modules/_gdbmmodule.c
--- Python-3.9.0/Modules/_gdbmmodule.c.17~	2020-10-18 20:11:06.336018040 +0200
+++ Python-3.9.0/Modules/_gdbmmodule.c	2020-10-18 20:11:45.349441470 +0200
@@ -133,6 +133,7 @@ dbm_length(dbmobject *dp)
             }
             okey=key;
         }
+	if(okey.dsize) free(okey.dptr);
         dp->di_size = size;
 #endif
     }