diff --git a/etc/mkuxn-fast.lua b/etc/mkuxn-fast.lua
index 7e40cd4..82fa0ec 100644
--- a/etc/mkuxn-fast.lua
+++ b/etc/mkuxn-fast.lua
@@ -324,6 +324,7 @@ evaluxn(Uxn *u, Uint16 vec)
 {
 	Uint8 instr;
 	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 b6f1a60..a0ce23d 100644
--- a/etc/mkuxn-fast.moon
+++ b/etc/mkuxn-fast.moon
@@ -232,6 +232,7 @@ evaluxn(Uxn *u, Uint16 vec)
 {
 	Uint8 instr;
 	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 c157e7a..ba09b14 100644
--- a/src/uxn-fast.c
+++ b/src/uxn-fast.c
@@ -56,6 +56,7 @@ evaluxn(Uxn *u, Uint16 vec)
 {
 	Uint8 instr;
 	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 13b3a8c..b40ea80 100644
--- a/src/uxn.c
+++ b/src/uxn.c
@@ -159,6 +159,7 @@ evaluxn(Uxn *u, Uint16 vec)
 	u->ram.ptr = vec;
 	u->wst.error = 0;
 	u->rst.error = 0;
+	if(u->wst.ptr > 0xf8) u->wst.ptr = 0xf8;
 	while(u->ram.ptr)
 		if(!stepuxn(u, u->ram.dat[u->ram.ptr++]))
 			return 0;