diff --git a/etc/mkuxn-fast.lua b/etc/mkuxn-fast.lua
index 21c31b2..8c15f72 100644
--- a/etc/mkuxn-fast.lua
+++ b/etc/mkuxn-fast.lua
@@ -322,6 +322,7 @@ uxn_eval(Uxn *u, Uint16 vec)
 	if(u->dev[0].dat[0xf]) 
 		return 0;
 	u->ram.ptr = vec;
+  if(u->wst.ptr > 0xf8) u->wst.ptr = 0xf8;
 	while(u->ram.ptr) {
 		instr = u->ram.dat[u->ram.ptr++];
 		switch(instr) {
diff --git a/etc/mkuxn-fast.moon b/etc/mkuxn-fast.moon
index c8ce667..4247bc5 100644
--- a/etc/mkuxn-fast.moon
+++ b/etc/mkuxn-fast.moon
@@ -231,6 +231,7 @@ uxn_eval(Uxn *u, Uint16 vec)
 	if(u->dev[0].dat[0xf]) 
 		return 0;
 	u->ram.ptr = vec;
+	if(u->wst.ptr > 0xf8) u->wst.ptr = 0xf8;
 	while(u->ram.ptr) {
 		instr = u->ram.dat[u->ram.ptr++];
 		switch(instr) {
diff --git a/src/uxn-fast.c b/src/uxn-fast.c
index ca462d2..9b74de6 100644
--- a/src/uxn-fast.c
+++ b/src/uxn-fast.c
@@ -45,6 +45,7 @@ uxn_eval(Uxn *u, Uint16 vec)
 	if(u->dev[0].dat[0xf]) 
 		return 0;
 	u->ram.ptr = vec;
+	if(u->wst.ptr > 0xf8) u->wst.ptr = 0xf8;
 	while(u->ram.ptr) {
 		instr = u->ram.dat[u->ram.ptr++];
 		switch(instr) {
diff --git a/src/uxn.c b/src/uxn.c
index 8015b48..bedb654 100644
--- a/src/uxn.c
+++ b/src/uxn.c
@@ -125,6 +125,7 @@ uxn_eval(Uxn *u, Uint16 vec)
 	if(u->dev[0].dat[0xf])
 		return 0;
 	u->ram.ptr = vec;
+	if(u->wst.ptr > 0xf8) u->wst.ptr = 0xf8;
 	while(u->ram.ptr) {
 		Uint8 instr = u->ram.dat[u->ram.ptr++];
 		/* Return Mode */