diff --git a/src/alloy/backend/ivm/ivm_intcode.cc b/src/alloy/backend/ivm/ivm_intcode.cc
index 77dd2c472..dfbb49545 100644
--- a/src/alloy/backend/ivm/ivm_intcode.cc
+++ b/src/alloy/backend/ivm/ivm_intcode.cc
@@ -45,6 +45,17 @@ namespace ivm {
 //#define DPRINT if (ics.thread_state->thread_id() == 1) printf
 //#define DFLUSH() fflush(stdout)
 
+#if XE_CPU_BIGENDIAN
+#define VECTORBYTEOFFSET(n) (n)
+#else
+static const uint8_t __vector_byte_offset_table[16] = {
+  3, 2, 1, 0,
+  7, 6, 5, 4,
+  11, 10, 9, 8,
+  15, 14, 13, 12,
+};
+#define VECTORBYTEOFFSET(n) (__vector_byte_offset_table[n])
+#endif
 
 uint32_t IntCode_INT_LOAD_CONSTANT(IntCodeState& ics, const IntCode* i) {
   // TODO(benvanik): optimize on type to avoid 16b copy per load.
@@ -1245,7 +1256,7 @@ uint32_t IntCode_LOAD_VECTOR_SHL(IntCodeState& ics, const IntCode* i) {
   int8_t sh = MIN(16, ics.rf[i->src1_reg].i8);
   vec128_t& dest = ics.rf[i->dest_reg].v128;
   for (int n = 0; n < 16; n++) {
-    dest.b16[n] = __lvsl_table[sh][n];
+    dest.b16[n] = __lvsl_table[sh][VECTORBYTEOFFSET(n)];
   }
   return IA_NEXT;
 }
@@ -1257,7 +1268,7 @@ uint32_t IntCode_LOAD_VECTOR_SHR(IntCodeState& ics, const IntCode* i) {
   int8_t sh = MIN(16, ics.rf[i->src1_reg].i8);
   vec128_t& dest = ics.rf[i->dest_reg].v128;
   for (int n = 0; n < 16; n++) {
-    dest.b16[n] = __lvsr_table[sh][n];
+    dest.b16[n] = __lvsr_table[sh][VECTORBYTEOFFSET(n)];
   }
   return IA_NEXT;
 }
@@ -3681,16 +3692,10 @@ uint32_t IntCode_PERMUTE_V128_BY_INT32(IntCodeState& ics, const IntCode* i) {
   }
   return IA_NEXT;
 }
-static const uint8_t __swap_table[16] = {
-  3, 2, 1, 0,
-  7, 6, 5, 4,
-  11, 10, 9, 8,
-  15, 14, 13, 12,
-};
 uint8_t grab(const vec128_t& src, uint8_t index) {
   return (index < 8
-      ? (src.low >> (__swap_table[index] << 3))
-      : (src.high >> ((__swap_table[index - 8]) << 3))) & 0xFF;
+      ? (src.low >> (VECTORBYTEOFFSET(index) << 3))
+      : (src.high >> ((VECTORBYTEOFFSET(index - 8)) << 3))) & 0xFF;
 }
 uint32_t IntCode_PERMUTE_V128_BY_V128(IntCodeState& ics, const IntCode* i) {
   const vec128_t& table = ics.rf[i->src1_reg].v128;
@@ -3699,12 +3704,12 @@ uint32_t IntCode_PERMUTE_V128_BY_V128(IntCodeState& ics, const IntCode* i) {
   vec128_t& dests = ics.rf[i->dest_reg].v128;
   dests.low = dests.high = 0;
   for (size_t n = 0; n < 16; n++) {
-    uint8_t index = table.b16[n] & 0x1F;
+    uint8_t index = table.b16[VECTORBYTEOFFSET(n)] & 0x1F;
     uint8_t value = index < 16
         ? grab(src2, index)
         : grab(src3, index - 16);
     uint64_t& dest = n < 8 ? dests.low : dests.high;
-    uint8_t shift = __swap_table[(n < 8 ? n : (n - 8))] << 3;
+    uint8_t shift = VECTORBYTEOFFSET((n < 8 ? n : (n - 8))) << 3;
     dest |= (((uint64_t)value) << shift);
   }
   return IA_NEXT;