diff --git a/w2c2/c.c b/w2c2/c.c
index 66a2117..92a1ecb 100644
--- a/w2c2/c.c
+++ b/w2c2/c.c
@@ -1045,8 +1045,9 @@ wasmCWriteLiteral(
             break;
         }
         case wasmValueTypeI64: {
+            MUST (stringBuilderAppend(builder, "W2C2_LL("))
             MUST (stringBuilderAppendI64(builder, value.i64))
-            MUST (stringBuilderAppend(builder, "ULL"))
+            MUST (stringBuilderAppend(builder, "U)"))
             break;
         }
         case wasmValueTypeF32: {
diff --git a/w2c2/w2c2_base.h b/w2c2/w2c2_base.h
index a31c10a..42e8d42 100644
--- a/w2c2/w2c2_base.h
+++ b/w2c2/w2c2_base.h
@@ -5,7 +5,7 @@
 #include <math.h>
 #include <string.h>
 #include <stdlib.h>
-#ifndef __NeXT__
+#if !(defined(__NeXT__) || (defined(_MSC_VER) && _MSC_VER <= 1000))
 #include <stdint.h>
 #endif
 
@@ -35,12 +35,23 @@ typedef signed short I16;
 typedef unsigned int U32;
 typedef signed int I32;
 
+#if defined(_MSC_VER) && _MSC_VER <= 1000
+typedef unsigned __int64 U64;
+typedef signed __int64 I64;
+#else
 typedef unsigned long long int U64;
 typedef signed long long int I64;
+#endif
 
 typedef float F32;
 typedef double F64;
 
+#if defined(_MSC_VER) && _MSC_VER <= 1000
+#define W2C2_LL(x) x ## i64
+#else
+#define W2C2_LL(x) x ## ll
+#endif
+
 #define MUST(_) { if (!(_)) { return false; }; }
 
 #define WASM_LITTLE_ENDIAN  0
@@ -144,14 +155,14 @@ typedef double F64;
                   | (((x) & 0x00FF0000) >> 8 ) \
                   | (((x) & 0x0000FF00) << 8 ) \
                   | (((x) & 0x000000FF) << 24))
-#define swapU64(x) ((((x) & 0xff00000000000000ull) >> 56) \
-                  | (((x) & 0x00ff000000000000ull) >> 40) \
-                  | (((x) & 0x0000ff0000000000ull) >> 24) \
-                  | (((x) & 0x000000ff00000000ull) >> 8 ) \
-                  | (((x) & 0x00000000ff000000ull) << 8 ) \
-                  | (((x) & 0x0000000000ff0000ull) << 24) \
-                  | (((x) & 0x000000000000ff00ull) << 40) \
-                  | (((x) & 0x00000000000000ffull) << 56))
+#define swapU64(x) ((((x) & W2C2_LL(0xff00000000000000u)) >> 56) \
+                  | (((x) & W2C2_LL(0x00ff000000000000u)) >> 40) \
+                  | (((x) & W2C2_LL(0x0000ff0000000000u)) >> 24) \
+                  | (((x) & W2C2_LL(0x000000ff00000000u)) >> 8 ) \
+                  | (((x) & W2C2_LL(0x00000000ff000000u)) << 8 ) \
+                  | (((x) & W2C2_LL(0x0000000000ff0000u)) << 24) \
+                  | (((x) & W2C2_LL(0x000000000000ff00u)) << 40) \
+                  | (((x) & W2C2_LL(0x00000000000000ffu)) << 56))
 
 #endif
 
@@ -186,11 +197,11 @@ typedef double F64;
 #endif
 
 #ifndef LLONG_MIN
-#define LLONG_MIN (-0x7fffffffffffffffLL-1)
+#define LLONG_MIN (W2C2_LL(-0x7fffffffffffffff)-1)
 #endif
 
 #ifndef LLONG_MAX
-#define LLONG_MAX 0x7fffffffffffffffLL
+#define LLONG_MAX W2C2_LL(0x7fffffffffffffff)
 #endif
 
 #ifndef INT32_MAX
@@ -202,7 +213,7 @@ typedef double F64;
 #endif
 
 #ifndef INT64_MAX
-#define INT64_MAX 9223372036854775807LL
+#define INT64_MAX W2C2_LL(9223372036854775807)
 #endif
 
 #ifndef INT64_MIN
@@ -214,7 +225,7 @@ typedef double F64;
 #endif
 
 #ifndef UINT64_MAX
-#define UINT64_MAX 18446744073709551615ULL
+#define UINT64_MAX W2C2_LL(18446744073709551615U)
 #endif
 
 #if defined(_MSC_VER) && _MSC_VER <= 1500
@@ -341,10 +352,10 @@ I32_POPCNT(
 static
 W2C2_INLINE
 U64 I64_POPCNT(U64 x) {
-    x -= ((x >> 1) & 0x5555555555555555ull);
-    x = ((x >> 2) & 0x3333333333333333ull) + (x & 0x3333333333333333ull);
-    x = ((x >> 4) + x) & 0xf0f0f0f0f0f0f0full;
-    x *= 0x101010101010101ull;
+    x -= ((x >> 1) & W2C2_LL(0x5555555555555555u));
+    x = ((x >> 2) & W2C2_LL(0x3333333333333333u)) + (x & W2C2_LL(0x3333333333333333u));
+    x = ((x >> 4) + x) & W2C2_LL(0xf0f0f0f0f0f0f0fu);
+    x *= W2C2_LL(0x101010101010101u);
     return (x >> 56);
 }
 #endif
@@ -1049,8 +1060,13 @@ DEFINE_SWAP(32, i, int)
 DEFINE_SWAP(32, I, unsigned int)
 DEFINE_SWAP(32, l, long)
 DEFINE_SWAP(32, L, unsigned long)
+#if defined(_MSC_VER) && _MSC_VER <= 1000
+DEFINE_SWAP(64, q, signed __int64)
+DEFINE_SWAP(64, Q, unsigned __int64)
+#else
 DEFINE_SWAP(64, q, long long)
 DEFINE_SWAP(64, Q, unsigned long long)
+#endif
 DEFINE_SWAP(32, f, float)
 DEFINE_SWAP(64, d, double)
 
@@ -1110,7 +1126,7 @@ typedef struct wasmModuleInstance {
 #define __has_extension __has_feature
 #endif
 
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && _MSC_VER >= 1500
 #define WASM_ATOMICS_MSVC
 #elif defined(__GNUC__) && (GCC_VERSION >= 40700 || __has_extension(c_atomic))
 #define WASM_ATOMICS_GCC
diff --git a/wasi/wasi.c b/wasi/wasi.c
index 3909f5c..4e59b17 100644
--- a/wasi/wasi.c
+++ b/wasi/wasi.c
@@ -10,8 +10,12 @@
 #endif /* HAS_UNISTD */
 
 #ifdef _MSC_VER
+#if _MSC_VER <= 1000
+typedef signed int ssize_t; /* assuming target machine is ILP32 ! */
+#else
 #include <BaseTsd.h>
 typedef SSIZE_T ssize_t;
+#endif
 #define INT64_C(val) val##i64
 #endif /* _MSC_VER */
 
@@ -1662,10 +1666,10 @@ WASI_IMPORT(U32, fd_close, (
 })
 
 #ifndef NSEC_PER_SEC
-#define NSEC_PER_SEC 1000000000LL
+#define NSEC_PER_SEC W2C2_LL(1000000000)
 #endif
 #ifndef NSEC_PER_USEC
-#define NSEC_PER_USEC 1000LL
+#define NSEC_PER_USEC W2C2_LL(1000)
 #endif
 
 static
@@ -3901,7 +3905,7 @@ wasiRandomGet(
 
     bufferStart = memory->data + bufferPointer;
 
-#ifdef _WIN32
+#if defined(_WIN32) && !(defined(_MSC_VER) && _MSC_VER <= 1000)
 #include <wincrypt.h>
     {
         HCRYPTPROV provider;
@@ -3970,7 +3974,7 @@ wasiRandomGet(
             return WASI_ERRNO_SUCCESS;
         }
     }
-#if defined(__MWERKS__) && defined(macintosh)
+#if (defined(__MWERKS__) && defined(macintosh)) || (defined(_MSC_VER) && _MSC_VER <= 1000)
     /* Fall back to rand */
     {
         U32 i = 0;
diff --git a/wasi/win32.h b/wasi/win32.h
index 9adca9a..6269bfd 100644
--- a/wasi/win32.h
+++ b/wasi/win32.h
@@ -8,6 +8,27 @@
 extern "C" {
 #endif
 
+/* defines for MSVC 4.0 */
+#ifndef ERROR_DELETE_PENDING
+#define ERROR_DELETE_PENDING 303
+#endif
+
+#ifndef ERROR_CANT_RESOLVE_FILENAME
+#define ERROR_CANT_RESOLVE_FILENAME 1921
+#endif
+
+#ifndef INVALID_FILE_ATTRIBUTES
+#define INVALID_FILE_ATTRIBUTES (~0u)
+#endif
+
+#ifndef FILE_ATTRIBUTE_REPARSE_POINT
+#define FILE_ATTRIBUTE_REPARSE_POINT 0x00000400
+#endif
+
+#ifndef IO_REPARSE_TAG_MOUNT_POINT
+#define IO_REPARSE_TAG_MOUNT_POINT 0xA0000003l
+#endif
+
 struct dirent {
     long d_ino;
     unsigned short d_reclen;