diff --git a/changelogs/unreleased/ghe-523-max-config-param-length.md b/changelogs/unreleased/ghe-523-max-config-param-length.md
new file mode 100644
index 0000000000000000000000000000000000000000..1276509f3839e328a549a876f35976028531de0c
--- /dev/null
+++ b/changelogs/unreleased/ghe-523-max-config-param-length.md
@@ -0,0 +1,3 @@
+## feature/box
+
+* The maximum length of `box.cfg{}` string parameters is now 512 instead of 256.
diff --git a/src/cfg.c b/src/cfg.c
index 1097538715712f76674258e60a6f3933f0c0d8d8..e5b6cbdc794c41ccb726bcc28911216ac9cc2adb 100644
--- a/src/cfg.c
+++ b/src/cfg.c
@@ -34,7 +34,7 @@
 #include "tt_static.h"
 #include "lua/uri.h"
 
-enum { MAX_OPT_NAME_LEN = 256, MAX_OPT_VAL_LEN = 256 };
+enum { MAX_OPT_NAME_LEN = 256, MAX_OPT_VAL_LEN = 512 };
 
 static void
 cfg_get(const char *param)