diff --git a/src/boards/406.c b/src/boards/406.c
index 49c1703..6bb41cd 100644
--- a/src/boards/406.c
+++ b/src/boards/406.c
@@ -22,7 +22,7 @@
 #include "mmc3.h"
 #include "flashrom.h"
 
-uint8 submapper;
+static uint8 submapper;
 
 static DECLFW(Write) {
 	flashrom_write(A &0x1FFF | (Page[A >>11] +A -PRGptr[0]) &~0x1FFF, V);
diff --git a/src/boards/480.c b/src/boards/480.c
index a7b73a8..dddd00b 100644
--- a/src/boards/480.c
+++ b/src/boards/480.c
@@ -21,7 +21,7 @@
 #include "mapinc.h"
 #include "mmc3.h"
 
-uint8 submapper;
+static uint8 submapper;
 static uint8 *CHRRAM =NULL;
 static uint32 CHRRAMSIZE;