diff --git a/src/cmd2F.c b/src/cmd2F.c
index 735b8ab..3271ba4 100644
--- a/src/cmd2F.c
+++ b/src/cmd2F.c
@@ -562,7 +562,7 @@ void commands2F52() {
 void commands2F53() {
 	int eFlag = getCaliValue();
 	
-	nact->patch_ec = eFlag;
+	nact->patch_ec = (eFlag == 1);
 	
 	TRACE("patchEC %d:", eFlag);
 }
@@ -936,7 +936,7 @@ void commands2F6F() {
 void commands2F70() {
 	int eFlag = getCaliValue();
 	
-	nact->patch_emen = eFlag;
+	nact->patch_emen = (eFlag == 1);
 	
 	TRACE("patchEMEN %d:", eFlag);
 }
@@ -1152,7 +1152,7 @@ void commands2F85() {
 void commands2F86() {
 	int eFlag = getCaliValue();
 	
-	nact->patch_g0 = eFlag;
+	nact->patch_g0 = (eFlag == 1);
 	
 	TRACE("patchG0 %d:", eFlag);
 }
diff --git a/src/cmde.c b/src/cmde.c
index b119e76..9d2f6f2 100644
--- a/src/cmde.c
+++ b/src/cmde.c
@@ -55,13 +55,13 @@ void commandEC() {
 	int num = getCaliValue();
 	Ecomtbl *e;
 	SDL_Rect *r;
+	int adj = nact->patch_ec ? 0 : -1;
 	
 	if (num == 0) {
 		r = &nact->ags.view_area;
-		ags_fillRectangle(r->x, r->y, r->w, r->h, 0);
-		ags_updateArea(r->x, r->y, r->w, r->h);
+		ags_fillRectangle(r->x, r->y, r->w + adj, r->h + adj, 0);
+		ags_updateArea(r->x, r->y, r->w + adj, r->h + adj);
 	} else {
-		int adj = (nact->patch_ec == 0) ? -1 : 0;
 		e = &tbl[num - 1];
 		ags_fillRectangle(e->r.x, e->r.y, e->r.w + adj, e->r.h + adj, e->pal);
 		ags_updateArea(e->r.x, e->r.y, e->r.w + adj, e->r.h + adj);
@@ -92,7 +92,7 @@ void commandEM() {
 
 	SDL_Point p = {x, y};
 	SDL_Rect r = tbl[num - 1].r;
-	if (nact->patch_emen == 0) {
+	if (!nact->patch_emen) {
 		r.w -= 1;
 		r.h -= 1;
 	}
@@ -112,7 +112,7 @@ void commandEN() {
 	
 	for (int i = min; i <= max; i++) {
 		SDL_Rect r = tbl[i - 1].r;
-		if (nact->patch_emen == 0) {
+		if (!nact->patch_emen) {
 			r.w -= 1;
 			r.h -= 1;
 		}
diff --git a/src/cmdy.c b/src/cmdy.c
index 048470d..aa6aab5 100644
--- a/src/cmdy.c
+++ b/src/cmdy.c
@@ -146,7 +146,7 @@ void commandY() {
 		}
 		break;
 	case 1900:
-		nact->patch_ec = p2;
+		nact->patch_ec = (p2 == 1);
 		// We're sure this game was built for System3.9 v5.50, which by default
 		// routes CD-DA commands to DRIFILE_WAVE.
 		muscd_init_bgm(DRIFILE_WAVE, 999);
diff --git a/src/nact.c b/src/nact.c
index 98eb281..9be7a1d 100644
--- a/src/nact.c
+++ b/src/nact.c
@@ -167,9 +167,9 @@ void nact_init() {
 
 	sel_init();
 
-	nact->patch_ec = 1;  // TODO: revisit
-	nact->patch_emen = 0;
-	nact->patch_g0 = 0;
+	nact->patch_ec = false;
+	nact->patch_emen = false;
+	nact->patch_g0 = false;
 
 	msg_msgHankakuMode = 0;
 }
diff --git a/src/nact.h b/src/nact.h
index 18f932d..4736fd0 100644
--- a/src/nact.h
+++ b/src/nact.h
@@ -97,10 +97,10 @@ typedef struct {
 	/* 選択肢関連 */
 	sel_t sel;
 	
-	/* patch 関連 */
-	int patch_ec;   /* see patch_ec command   */
-	int patch_emen; /* see patch_emen command */
-	int patch_g0;   /* see patch g0 command */
+	/* patch flags */
+	bool patch_ec;
+	bool patch_emen;
+	bool patch_g0;
 
 	/* ain 関連 */
 	S39AIN ain;
diff --git a/test/patchec.adv b/test/patchec.adv
new file mode 100644
index 0000000..2ee3107
--- /dev/null
+++ b/test/patchec.adv
@@ -0,0 +1,46 @@
+	MS FILE,"patchec.adv":
+
+	; --- EC with a registered rectangle ---
+	; patchEC defaults to off, so EC clears a region 1px narrower and
+	; shorter than the rectangle registered by ES.
+	CF 100,100,40,30,7:
+	ES 1,3,100,100,40,30:
+	EC 1:
+	PT0 RND,120,115: ~AssertEquals RND,3,__LINE__:
+	PT0 RND,138,128: ~AssertEquals RND,3,__LINE__:
+	PT0 RND,139,115: ~AssertEquals RND,7,__LINE__:
+	PT0 RND,120,129: ~AssertEquals RND,7,__LINE__:
+
+	; patchEC 1 disables the adjustment, so EC clears the whole rectangle.
+	CF 100,100,40,30,7:
+	patchEC 1:
+	EC 1:
+	PT0 RND,139,115: ~AssertEquals RND,3,__LINE__:
+	PT0 RND,120,129: ~AssertEquals RND,3,__LINE__:
+
+	; Only eFlag == 1 turns the patch on; any other value restores the bug.
+	CF 100,100,40,30,7:
+	patchEC 2:
+	EC 1:
+	PT0 RND,139,115: ~AssertEquals RND,7,__LINE__:
+	patchEC 0:
+
+	; --- EC 0 clears the current view area, now with the same adjustment ---
+	ZZ5 D18:
+	WV 100,100,50,40:
+	CF 100,100,50,40,7:
+	EC 0:
+	PT0 RND,120,120: ~AssertEquals RND,0,__LINE__:
+	PT0 RND,148,138: ~AssertEquals RND,0,__LINE__:
+	PT0 RND,149,120: ~AssertEquals RND,7,__LINE__:
+	PT0 RND,120,139: ~AssertEquals RND,7,__LINE__:
+
+	CF 100,100,50,40,7:
+	patchEC 1:
+	EC 0:
+	PT0 RND,149,120: ~AssertEquals RND,0,__LINE__:
+	PT0 RND,120,139: ~AssertEquals RND,0,__LINE__:
+	patchEC 0:
+	WV 0,0,D18,D19:
+
+	%0:
diff --git a/test/patchemen.adv b/test/patchemen.adv
new file mode 100644
index 0000000..78640b9
--- /dev/null
+++ b/test/patchemen.adv
@@ -0,0 +1,36 @@
+	MS FILE,"patchemen.adv":
+
+	ES 1,0,10,10,20,20:
+	ES 2,0,20,20,20,20:
+
+	; --- EM: point-in-rectangle test ---
+	; patchEMEN defaults to off, so the rectangle is treated as 1px
+	; narrower and shorter than registered by ES.
+	EM 1,RND,10,10: ~AssertEquals RND,1,__LINE__:
+	EM 1,RND,28,28: ~AssertEquals RND,1,__LINE__:
+	EM 1,RND,29,20: ~AssertEquals RND,0,__LINE__:
+	EM 1,RND,20,29: ~AssertEquals RND,0,__LINE__:
+	EM 1,RND,9,10:  ~AssertEquals RND,0,__LINE__:
+
+	; patchEMEN 1 disables the adjustment.
+	patchEMEN 1:
+	EM 1,RND,29,29: ~AssertEquals RND,1,__LINE__:
+	EM 1,RND,30,20: ~AssertEquals RND,0,__LINE__:
+
+	; Only eFlag == 1 turns the patch on; any other value restores the bug.
+	patchEMEN 2:
+	EM 1,RND,29,29: ~AssertEquals RND,0,__LINE__:
+	patchEMEN 0:
+
+	; --- EN: number of the rectangle containing the point ---
+	EN RND,1,2,15,15: ~AssertEquals RND,1,__LINE__:
+	EN RND,1,2,25,25: ~AssertEquals RND,2,__LINE__:
+	EN RND,1,2,5,5:   ~AssertEquals RND,0,__LINE__:
+
+	; The patch flag also applies to EN's edge handling.
+	EN RND,1,1,29,29: ~AssertEquals RND,0,__LINE__:
+	patchEMEN 1:
+	EN RND,1,1,29,29: ~AssertEquals RND,1,__LINE__:
+	patchEMEN 0:
+
+	%0:
diff --git a/test/test.adv b/test/test.adv
index e428312..b88332b 100644
--- a/test/test.adv
+++ b/test/test.adv
@@ -16,6 +16,8 @@
 	%#math.adv:
 	%#variable.adv:
 	%#unitmap.adv:
+	%#patchec.adv:
+	%#patchemen.adv:
 
 	HH0,tests_passed: ' tests passed' R
 	HH0,tests_failed: ' tests failed' R
diff --git a/test/test.hed b/test/test.hed
index 3ac2c81..2627d35 100644
--- a/test/test.hed
+++ b/test/test.hed
@@ -8,6 +8,8 @@ stack.adv
 math.adv
 variable.adv
 unitmap.adv
+patchec.adv
+patchemen.adv
 
 #DLLHeader
 ShString.HEL
diff --git a/test/testSA.ALD b/test/testSA.ALD
index df84e3d..538471d 100644
Binary files a/test/testSA.ALD and b/test/testSA.ALD differ