diff --git a/buff.h b/buff.h
index 9b75fd4..666dc00 100644
--- a/buff.h
+++ b/buff.h
@@ -20,3 +20,15 @@
 #define BUFF_REMOVE_FRONT(buff_ptr) {if((buff_ptr)->cur_index > 0) {for(int i = 0; i < (buff_ptr)->cur_index - 1; i++) { (buff_ptr)->data[i] = (buff_ptr)->data[i+1]; }; (buff_ptr)->cur_index--;}}
 #define BUFF_REMOVE_AT_INDEX(buff_ptr, index) { BUFF_VALID(buff_ptr); assert(index >= 0); assert(index < (buff_ptr)->cur_index); for(int i = index; i < (buff_ptr)->cur_index - 1; i++) (buff_ptr)->data[i] = (buff_ptr)->data[i + 1]; (buff_ptr)->cur_index -= 1; }
 #define BUFF_CLEAR(buff_ptr) {memset((buff_ptr), 0, sizeof(*(buff_ptr)));  ((buff_ptr)->cur_index = 0);}
+
+typedef struct
+{
+ void *data;
+ size_t max_data_elems;
+ size_t data_elem_size;
+ int *cur_index;
+} BuffRef;
+
+#define BUFF_MAKEREF(buff_ptr) ((BuffRef){.data = (void*)((buff_ptr)->data), .max_data_elems = ARRLEN((buff_ptr)->data), .data_elem_size = sizeof((buff_ptr)->data[0]), .cur_index = &((buff_ptr)->cur_index)})
+
+
diff --git a/makeprompt.h b/makeprompt.h
index 7a1f984..bf5533e 100644
--- a/makeprompt.h
+++ b/makeprompt.h
@@ -405,7 +405,26 @@ void process_perception(Entity *it, Perception p)
  }
 }
 
-#define printf_buff(buff_ptr, ...) { BUFF_VALID(buff_ptr); int written = snprintf((buff_ptr)->data+(buff_ptr)->cur_index, ARRLEN((buff_ptr)->data) - (buff_ptr)->cur_index, __VA_ARGS__); assert(written >= 0); (buff_ptr)->cur_index += written; };
+// returns if printed into the buff without any errors
+bool printf_buff_impl(BuffRef into, const char *format, ...)
+{
+ assert(*into.cur_index < into.max_data_elems);
+ assert(into.data_elem_size == 1); // characters
+ va_list args;
+ va_start (args, format);
+ int n = info.max_data_elems - *info.cur_index;
+ int written = vsnprintf((char*)into.data + *info.cur_index, n, format, args);
+
+ // https://cplusplus.com/reference/cstdio/vsnprintf/
+ bool succeeded = true;
+ if(written < 0) succeeded = false; // encoding error
+ if(written >= n) succeeded = false; // didn't fit in buffer
+
+ va_end(args);
+ return succeeded;
+}
+
+#define printf_buff(buff_ptr, ...) printf_buff_impl(BUFF_MAKEREF(buff_ptr), __VA_ARGS__)
 
 bool npc_does_dialog(Entity *it)
 {