diff --git a/23_day/a_nask.nas b/23_day/a_nask.nas
index aec636e..7d87957 100644
--- a/23_day/a_nask.nas
+++ b/23_day/a_nask.nas
@@ -15,6 +15,7 @@
 		GLOBAL	_api_point
 		GLOBAL	_api_refreshwin
 		GLOBAL	_api_linewin
+		GLOBAL	_api_closewin
 
 [SECTION .text]
 
@@ -170,3 +171,11 @@ _api_linewin:		; void api_linewin(int win, int x0, int y0, int x1, int y1, int c
 		POP		ESI
 		POP		EDI
 		RET
+
+_api_closewin:		; void api_closewin(int win);
+		PUSH	EBX
+		MOV		EDX,14
+		MOV		EBX,[ESP+8]	; win
+		INT		0x40
+		POP		EBX
+		RET
diff --git a/23_day/console.c b/23_day/console.c
index b7d65ad..dbc9b30 100644
--- a/23_day/console.c
+++ b/23_day/console.c
@@ -373,6 +373,8 @@ int *hrb_api(int edi, int esi, int ebp, int esp, int ebx, int edx, int ecx, int
 		if ((ebx & 1) == 0) {
 			sheet_refresh(sht, eax, ecx, esi + 1, edi + 1);
 		}
+	} else if (edx == 14) {
+		sheet_free((struct SHEET *) ebx);
 	}
 	return 0;
 }
diff --git a/23_day/lines.c b/23_day/lines.c
index 8cef008..1b5d926 100644
--- a/23_day/lines.c
+++ b/23_day/lines.c
@@ -3,6 +3,7 @@ void api_initmalloc(void);
 char *api_malloc(int size);
 void api_refreshwin(int win, int x0, int y0, int x1, int y1);
 void api_linewin(int win, int x0, int y0, int x1, int y1, int col);
+void api_closewin(int win);
 void api_end(void);
 
 void HariMain(void)
@@ -17,5 +18,6 @@ void HariMain(void)
 		api_linewin(win + 1, 88, 26, i * 9 + 88, 89, i);
 	}
 	api_refreshwin(win,  6, 26, 154, 90);
+	api_closewin(win);
 	api_end();
 }