diff --git a/src/config.h.in b/src/config.h.in
index ab861bd..65c4934 100644
--- a/src/config.h.in
+++ b/src/config.h.in
@@ -15,6 +15,9 @@
 #ifndef LY_CONFIG_H_
 #define LY_CONFIG_H_
 
+/** size of fixed_mem in lyd_value, minimum is 8 (B) */
+#define LYD_VALUE_FIXED_MEM_SIZE @LYD_VALUE_SIZE@
+
 /*
  * Plugins
  */