diff --git a/src/uxn.h b/src/uxn.h
index 9aeb72a..2359c47 100644
--- a/src/uxn.h
+++ b/src/uxn.h
@@ -16,6 +16,8 @@ typedef signed short Sint16;
 typedef unsigned int Uint32;
 
 #define PAGE_PROGRAM 0x0100
+#define PAGE_WST 0xfe00
+#define PAGE_RST 0xff00
 
 /* clang-format off */
 
diff --git a/src/uxncli.c b/src/uxncli.c
index d2d4605..8966ea4 100644
--- a/src/uxncli.c
+++ b/src/uxncli.c
@@ -143,7 +143,7 @@ main(int argc, char **argv)
 
 	shadow = (Uint8 *)calloc(0xffff, sizeof(Uint8));
 	memory = (Uint8 *)calloc(0xffff, sizeof(Uint8));
-	if(!uxn_boot(&u, (Stack *)(shadow + 0x200), (Stack *)(shadow + 0x400), memory))
+	if(!uxn_boot(&u, (Stack *)(shadow + PAGE_WST), (Stack *)(shadow + PAGE_RST), memory))
 		return error("Boot", "Failed");
 
 	/* system   */ devsystem = uxn_port(&u, 0x0, system_dei, system_deo);
diff --git a/src/uxnemu.c b/src/uxnemu.c
index 4a4a23c..40881d2 100644
--- a/src/uxnemu.c
+++ b/src/uxnemu.c
@@ -280,7 +280,7 @@ start(Uxn *u, char *rom)
 
 	if(!uxn_boot(&hypervisor, (Stack *)(shadow + 0xfc00), (Stack *)(shadow + 0xfd00), shadow))
 		return error("Boot", "Failed to start uxn.");
-	if(!uxn_boot(u, (Stack *)(shadow + 0xfe00), (Stack *)(shadow + 0xff00), memory))
+	if(!uxn_boot(u, (Stack *)(shadow + PAGE_WST), (Stack *)(shadow + PAGE_RST), memory))
 		return error("Boot", "Failed to start uxn.");
 	if(!load(&hypervisor, "hypervisor.rom"))
 		error("Hypervisor", "No debugger found.");