diff --git a/src/uxn-fast.c b/src/uxn-fast.c
index 9b1b725..fba26ba 100644
--- a/src/uxn-fast.c
+++ b/src/uxn-fast.c
@@ -34,7 +34,7 @@ WITH REGARD TO THIS SOFTWARE.
 #define PUT2(o, v) { tmp = (v); s->dat[s->ptr - o - 2] = tmp >> 8; s->dat[s->ptr - o - 1] = tmp; }
 #define PUSH(stack, v) { stack->dat[stack->ptr++] = (v); }
 #define PUSH2(stack, v) { tmp = (v); stack->dat[stack->ptr] = (v) >> 8; stack->dat[stack->ptr + 1] = (v); stack->ptr += 2; }
-#define SEND(a, b) { u->dev[a] = b; if((callbacks[(a) >> 4] >> ((a) & 0xf)) & 0x1) u->deo(u, a, b); }
+#define SEND(a, b) { u->dev[a] = b; if((callbacks[(a) >> 4] >> ((a) & 0xf)) & 0x1) u->deo(u, a); }
 
 static 
 Uint16 callbacks[] = {
diff --git a/src/uxn.h b/src/uxn.h
index bcfc489..cb114dd 100644
--- a/src/uxn.h
+++ b/src/uxn.h
@@ -32,11 +32,11 @@ typedef struct Uxn {
 	Uint8 *ram, *dev;
 	Stack *wst, *rst;
 	Uint8 (*dei)(struct Uxn *u, Uint8 addr);
-	void (*deo)(struct Uxn *u, Uint8 addr, Uint8 value);
+	void (*deo)(struct Uxn *u, Uint8 addr);
 } Uxn;
 
 typedef Uint8 Dei(Uxn *u, Uint8 addr);
-typedef void Deo(Uxn *u, Uint8 addr, Uint8 value);
+typedef void Deo(Uxn *u, Uint8 addr);
 
 int uxn_halt(Uxn *u, Uint8 instr, Uint8 err, Uint16 addr);
 int uxn_boot(Uxn *u, Uint8 *ram, Dei *dei, Deo *deo);
diff --git a/src/uxncli.c b/src/uxncli.c
index bb38ce3..d8d4a63 100644
--- a/src/uxncli.c
+++ b/src/uxncli.c
@@ -60,7 +60,7 @@ emu_dei(Uxn *u, Uint8 addr)
 }
 
 static void
-emu_deo(Uxn *u, Uint8 addr, Uint8 v)
+emu_deo(Uxn *u, Uint8 addr)
 {
 	Uint8 p = addr & 0x0f, d = addr & 0xf0;
 	switch(d) {
diff --git a/src/uxnemu.c b/src/uxnemu.c
index 3408734..47186b7 100644
--- a/src/uxnemu.c
+++ b/src/uxnemu.c
@@ -126,7 +126,7 @@ emu_dei(Uxn *u, Uint8 addr)
 }
 
 static void
-emu_deo(Uxn *u, Uint8 addr, Uint8 v)
+emu_deo(Uxn *u, Uint8 addr)
 {
 	Uint8 p = addr & 0x0f, d = addr & 0xf0;
 	switch(d) {