diff --git a/src/video/ataricommon/SDL_biosevents.c b/src/video/ataricommon/SDL_biosevents.c
index af4b7b72c..41efcabf9 100644
--- a/src/video/ataricommon/SDL_biosevents.c
+++ b/src/video/ataricommon/SDL_biosevents.c
@@ -74,7 +74,7 @@ void AtariBios_InitOSKeymap(_THIS)
 	SDL_memset(bios_previouskeyboard, 0, sizeof(bios_previouskeyboard));
 
 	/* Initialize keymap */
-	for ( i=0; i<sizeof(keymap); i++ )
+	for ( i=0; i<ATARIBIOS_MAXKEYS; i++ )
 		keymap[i] = SDLK_UNKNOWN;
 
 	/* Functions keys */
diff --git a/src/video/ataricommon/SDL_gemdosevents.c b/src/video/ataricommon/SDL_gemdosevents.c
index 9f28ca9bc..d4c209fc9 100644
--- a/src/video/ataricommon/SDL_gemdosevents.c
+++ b/src/video/ataricommon/SDL_gemdosevents.c
@@ -79,7 +79,7 @@ void AtariGemdos_InitOSKeymap(_THIS)
 	SDL_memset(gemdos_previouskeyboard, 0, sizeof(gemdos_previouskeyboard));
 
 	/* Initialize keymap */
-	for ( i=0; i<sizeof(keymap); i++ )
+	for ( i=0; i<ATARIBIOS_MAXKEYS; i++ )
 		keymap[i] = SDLK_UNKNOWN;
 
 	/* Functions keys */
diff --git a/src/video/ataricommon/SDL_ikbdevents.c b/src/video/ataricommon/SDL_ikbdevents.c
index 5c0b8347b..928a3bab5 100644
--- a/src/video/ataricommon/SDL_ikbdevents.c
+++ b/src/video/ataricommon/SDL_ikbdevents.c
@@ -79,7 +79,7 @@ void AtariIkbd_InitOSKeymap(_THIS)
 	SDL_memset(SDL_AtariIkbd_keyboard, KEY_UNDEFINED, ATARIBIOS_MAXKEYS);
 
 	/* Initialize keymap */
-	for ( i=0; i<sizeof(keymap); i++ )
+	for ( i=0; i<ATARIBIOS_MAXKEYS; i++ )
 		keymap[i] = SDLK_UNKNOWN;
 
 	/* Functions keys */
diff --git a/src/video/gem/SDL_gemevents.c b/src/video/gem/SDL_gemevents.c
index 09d6fa85b..c59a6ee50 100644
--- a/src/video/gem/SDL_gemevents.c
+++ b/src/video/gem/SDL_gemevents.c
@@ -93,7 +93,7 @@ void GEM_InitOSKeymap(_THIS)
 	SDL_memset(gem_currentascii, 0, sizeof(gem_currentascii));
 
 	/* Initialize keymap */
-	for ( i=0; i<sizeof(keymap); i++ )
+	for ( i=0; i<ATARIBIOS_MAXKEYS; i++ )
 		keymap[i] = SDLK_UNKNOWN;
 
 	/* Functions keys */