An Amulet compiler patch causes this to not crash.

mem/int.ml

@@ -24,8 +24,8 @@ instance decode s8 begin
   let decode addr =
     let u8 = Dolphin.read_value_8 addr
     let signfix =
-      if u8 > 127 then
-        negate (256 - u8)
+      if u8 > 0xFF then
+        negate (0x100 - u8)
       else
         u8
     S8 signfix
@@ -53,8 +53,8 @@ instance decode s16 begin
   let decode addr =
     let u16 = Dolphin.read_value_16 addr
     let signfix =
-      if u16 > 32767 then
-        negate (65536 - u16)
+      if u16 > 0xFFFF then
+        negate (0x10000 - u16)
       else
         u16
     S16 signfix
@@ -67,15 +67,24 @@ instance show u32 begin
   let show (U32 x) = (show x) ^ "_u32"
 end
 
+instance decode u32 begin
+  let decode addr = U32 (Dolphin.read_value_32 addr)
+end
+
 type s32 =
   S32 of int
 
 instance show s32 begin
-  let show (S32 x) =
-    let signfix =
-      if x > 2147483647 then
-        negate (4294967296 - x)
-      else
-        x
-  (show signfix) ^ "_s32"
+  let show (S32 x) = (show x) ^ "_s32"
+end
+
+instance decode s32 begin
+  let decode addr =
+    let u32 = Dolphin.read_value_32 addr
+    let signfix =
+      if u32 > 0xFFFFFFFF then
+        negate (0x100000000 - u32)
+      else
+        u32
+    S32 signfix
 end