diff --git a/include/neuron/type.h b/include/neuron/type.h
index dcad7fb6..24f81a65 100644
--- a/include/neuron/type.h
+++ b/include/neuron/type.h
@@ -155,7 +155,7 @@ typedef struct {
     uint8_t *  ptr;
 } neu_value_ptr_t;
 
-#define NEU_VALUE_SIZE 512
+#define NEU_VALUE_SIZE 256
 #define NEU_ARRAY_SIZE 128
 
 typedef struct {