diff --git a/libs/master.lib/dos_free.asm b/libs/master.lib/dos_free.asm
new file mode 100644
index 00000000..46762958
--- /dev/null
+++ b/libs/master.lib/dos_free.asm
@@ -0,0 +1,52 @@
+; master library - MSDOS
+;
+; Description:
+;	メインメモリブロックの開放
+;
+; Function/Procedures:
+;	void mem_free( unsigned seg ) ;
+;	void dos_free( unsigned seg ) ;		※この二つは同じものです
+;
+; Parameters:
+;	unsigned seg	DOSメモリブロックのセグメント
+;
+; Returns:
+;	None
+;
+; Binding Target:
+;	Microsoft-C / Turbo-C / Turbo Pascal
+;
+; Running Target:
+;	MS-DOS
+;
+; Requiring Resources:
+;	CPU: 8086
+;	DOS: 2.0 or later
+;
+; Notes:
+;	AX以外の全レジスタを保存します
+;
+; Compiler/Assembler:
+;	TASM 3.0
+;	OPTASM 1.6
+;
+; Author:
+;	恋塚昭彦
+;
+; Revision History:
+;	93/ 1/31 Initial dosfree.asm(from memalloc.asm)
+;	93/ 3/29 があんbugfix
+
+	public DOS_FREE
+func MEM_FREE
+DOS_FREE label CALLMODEL
+	push	BP
+	push	ES
+	mov	BP,SP
+	mov	ES,[BP+(RETSIZE+2)*2]	; seg
+	mov	AH,49h
+	int	21h
+	pop	ES
+	pop	BP
+	ret	2
+endfunc
diff --git a/th01_op.asm b/th01_op.asm
index 3058a32f..2d9f238c 100644
--- a/th01_op.asm
+++ b/th01_op.asm
@@ -1875,27 +1875,7 @@ include libs/master.lib/file_read.asm
 include libs/master.lib/file_close.asm
 include libs/master.lib/file_ropen.asm
 include libs/master.lib/file_seek.asm
-
-; =============== S U B	R O U T	I N E =======================================
-
-; Attributes: bp-based frame
-
-sub_1186	proc far
-
-arg_0		= word ptr  8
-
-		push	bp
-		push	es
-		mov	bp, sp
-		mov	es, [bp+arg_0]
-		mov	ah, 49h
-		int	21h		; DOS -	2+ - FREE MEMORY
-					; ES = segment address of area to be freed
-		pop	es
-		pop	bp
-		retf	2
-sub_1186	endp
-
+include libs/master.lib/dos_free.asm
 
 ; =============== S U B	R O U T	I N E =======================================
 
@@ -15992,7 +15972,7 @@ sub_E3C5	proc far
 		or	si, si
 		jz	short loc_E3E2
 		push	si
-		call	sub_1186
+		call	dos_free
 
 loc_E3E2:
 		pop	si
diff --git a/th01_reiiden.asm b/th01_reiiden.asm
index 62b4e2ef..9bfa2271 100644
--- a/th01_reiiden.asm
+++ b/th01_reiiden.asm
@@ -1999,27 +1999,7 @@ include libs/master.lib/file_ropen.asm
 include libs/master.lib/file_write.asm
 include libs/master.lib/file_create.asm
 include libs/master.lib/file_seek.asm
-
-; =============== S U B	R O U T	I N E =======================================
-
-; Attributes: bp-based frame
-
-sub_12D2	proc far
-
-arg_0		= word ptr  8
-
-		push	bp
-		push	es
-		mov	bp, sp
-		mov	es, [bp+arg_0]
-		mov	ah, 49h
-		int	21h		; DOS -	2+ - FREE MEMORY
-					; ES = segment address of area to be freed
-		pop	es
-		pop	bp
-		retf	2
-sub_12D2	endp
-
+include libs/master.lib/dos_free.asm
 include libs/master.lib/dos_axdx.asm
 
 ; =============== S U B	R O U T	I N E =======================================
@@ -23586,9 +23566,7 @@ sub_11718	proc far
 		or	si, si
 		jz	short loc_11735
 		push	si
-
-loc_11730:
-		call	sub_12D2
+		call	dos_free
 
 loc_11735:
 		pop	si