diff --git a/src/timer/mint/SDL_vbltimer.S b/src/timer/mint/SDL_vbltimer.S
index 5ea98cec1..2073ead67 100644
--- a/src/timer/mint/SDL_vbltimer.S
+++ b/src/timer/mint/SDL_vbltimer.S
@@ -110,10 +110,6 @@ badvector:
 
 /*--- Our vbl ---*/
 
-	.text
-	.even
-	.ascii "XBRA"
-	.ascii "_SDL"
 _my_vbl:
 	/* Verify if this is not already running */
 
diff --git a/src/video/ataricommon/SDL_ikbdinterrupt.S b/src/video/ataricommon/SDL_ikbdinterrupt.S
index b37ca9c89..1c87dee7e 100644
--- a/src/video/ataricommon/SDL_ikbdinterrupt.S
+++ b/src/video/ataricommon/SDL_ikbdinterrupt.S
@@ -119,8 +119,6 @@ ikbd_finbuffer:
 
 	.data
 	.even
-	.comm	old_ikbd,4*1
-	.even
 	.comm	ikbd_ierb,4*1
 	.even
 	.comm	ikbd_imrb,4*1
@@ -130,7 +128,8 @@ ikbd_finbuffer:
 	.text
 	.even
 	.ascii	"XBRA"
-	.ascii	"_SDL"
+	.ascii	"LSDL"
+	.comm	old_ikbd,4*1
 ikbd:
 	moveml	d0-d1/a0,sp@-
 	moveb	0xfffffc02:w,d0
diff --git a/src/video/ataricommon/SDL_xbiosmouseinterrupt.S b/src/video/ataricommon/SDL_xbiosmouseinterrupt.S
index 087947f61..71554e778 100644
--- a/src/video/ataricommon/SDL_xbiosmouseinterrupt.S
+++ b/src/video/ataricommon/SDL_xbiosmouseinterrupt.S
@@ -69,7 +69,8 @@ _SDL_AtariXbiosMouseInstall:
 	.text
 	.even
 	.ascii "XBRA"
-	.ascii "_SDL"
+	.ascii "LSDL"
+	.comm	oldvector,4*1
 _SDL_AtariXbiosMouseVector:
 	moveml	d0/a1,sp@-
 
@@ -96,10 +97,6 @@ _SDL_AtariXbiosMouseVector:
 	rts
 
 	.data
-	
-	.even
-	.comm	oldvector,4*1
-
 	.even
 	.comm	_SDL_AtariXbios_mousex,2*1
 	.even
diff --git a/src/video/xbios/SDL_xbios.c b/src/video/xbios/SDL_xbios.c
index aceb996ab..b96817085 100644
--- a/src/video/xbios/SDL_xbios.c
+++ b/src/video/xbios/SDL_xbios.c
@@ -490,6 +490,7 @@ static SDL_Surface *XBIOS_SetVideoMode(_THIS, SDL_Surface *current,
 			SDL_SetError("XBIOS_SetVideoMode: Not enough memory for shadow surface");
 			return (NULL);
 		}
+		memset(XBIOS_shadowscreen, 0, new_screen_size);
 	}
 
 	/* Output buffer needs to be twice in size for the software double-line mode */
@@ -506,6 +507,7 @@ static SDL_Surface *XBIOS_SetVideoMode(_THIS, SDL_Surface *current,
 		SDL_SetError("XBIOS_SetVideoMode: Not enough memory for video buffer");
 		return (NULL);
 	}
+	memset(XBIOS_screensmem[0], 0, new_screen_size);
 
 	XBIOS_screens[0]=(void *) (( (long) XBIOS_screensmem[0]+256) & 0xFFFFFF00UL);
 
@@ -518,6 +520,7 @@ static SDL_Surface *XBIOS_SetVideoMode(_THIS, SDL_Surface *current,
 			SDL_SetError("XBIOS_SetVideoMode: Not enough memory for double buffer");
 			return (NULL);
 		}
+		memset(XBIOS_screensmem[1], 0, new_screen_size);
 
 		XBIOS_screens[1]=(void *) (( (long) XBIOS_screensmem[1]+256) & 0xFFFFFF00UL);
 		modeflags |= SDL_DOUBLEBUF;