diff --git a/examples/slu4-minimal-64/software/mandelbrot16.min64 b/examples/slu4-minimal-64/software/mandelbrot16.min64
index 7acd792..ab5bd8e 100644
--- a/examples/slu4-minimal-64/software/mandelbrot16.min64
+++ b/examples/slu4-minimal-64/software/mandelbrot16.min64
@@ -13,8 +13,8 @@ IMAGE_Y_PIXELS = 240
 SCALE_BITS = 9
 SCALE_FACTOR = (1 << SCALE_BITS)
 
-MANDELBROT_START_X = -2*SCALE_FACTOR
-MANDELBROT_END_X = 1*SCALE_FACTOR
+MANDELBROT_START_X = -175*SCALE_FACTOR/100
+MANDELBROT_END_X = 125*SCALE_FACTOR/100
 MANDELBROT_STEP_X = (MANDELBROT_END_X - MANDELBROT_START_X)/IMAGE_X_PIXELS
 
 MANDELBROT_START_Y = -1*SCALE_FACTOR
diff --git a/examples/slu4-minimal-64/software/stringlib.min64 b/examples/slu4-minimal-64/software/stringlib.min64
index dbf8209..fc3e87d 100644
--- a/examples/slu4-minimal-64/software/stringlib.min64
+++ b/examples/slu4-minimal-64/software/stringlib.min64
@@ -172,16 +172,8 @@ int32_to_decimal_cstr:
     ; first determine if value is signed, remember stack is in big endian
     lds 1 ani %10000000 sta .is_signed
     cpi 0 beq .cacluate_str
-    ; it is negative, take 2's by first doing 1's then adding 1
-    lds 1 not sts 1
-    lds 2 not sts 2
-    lds 3 not sts 3
-    lds 4 not sts 4
-    ; now add 1, remember stack is in big endian
-    lds 4 adi 1 sts 4
-    lds 3 aci 0 sts 3
-    lds 2 aci 0 sts 2
-    lds 1 aci 0 sts 1
+    ; it is negative, take 2's
+    twos4s 1
 .cacluate_str:
     jps uint32_to_decimal_cstr
     pls4                ; remove pushed value