diff --git a/include/polarssl/bignum.h b/include/polarssl/bignum.h
index 9cf61a3fc3..b4a6c06379 100644
--- a/include/polarssl/bignum.h
+++ b/include/polarssl/bignum.h
@@ -109,25 +109,41 @@ typedef UINT64 uint64_t;
 typedef   signed char  t_sint;
 typedef unsigned char  t_uint;
 typedef uint16_t       t_udbl;
+#define POLARSSL_HAVE_UDBL
 #else
 #if defined(POLARSSL_HAVE_INT16)
 typedef  int16_t t_sint;
 typedef uint16_t t_uint;
 typedef uint32_t t_udbl;
+#define POLARSSL_HAVE_UDBL
 #else
-  typedef  int32_t t_sint;
-  typedef uint32_t t_uint;
-  #if ( defined(_MSC_VER) && defined(_M_IX86) )      || \
-      ( defined(__GNUC__) && (                          \
-        defined(__amd64__) || defined(__x86_64__)    || \
-        defined(__ppc64__) || defined(__powerpc64__) || \
-        defined(__ia64__)  || defined(__alpha__)     || \
-        (defined(__sparc__) && defined(__arch64__))  || \
-        defined(__s390x__) ) )
-      #define POLARSSL_HAVE_INT64
-  #endif
-  #if defined(POLARSSL_HAVE_INT64)
-    typedef uint64_t t_udbl;
+  #if ( defined(__MSC_VER) && defined(_M_AMD64) )
+    typedef  int64_t t_sint;
+    typedef uint64_t t_uint;
+  #else
+    #if ( defined(__GNUC__) && (                          \
+          defined(__amd64__) || defined(__x86_64__)    || \
+          defined(__ppc64__) || defined(__powerpc64__) || \
+          defined(__ia64__)  || defined(__alpha__)     || \
+          (defined(__sparc__) && defined(__arch64__))  || \
+          defined(__s390x__) ) )
+       typedef  int64_t t_sint;
+       typedef uint64_t t_uint;
+       typedef unsigned int t_udbl __attribute__((mode(TI)));
+       #define POLARSSL_HAVE_UDBL
+    #else
+       typedef  int32_t t_sint;
+       typedef uint32_t t_uint;
+       #if ( defined(_MSC_VER) && defined(_M_IX86) )
+         typedef uint64_t t_udbl;
+         #define POLARSSL_HAVE_UDBL
+       #else
+         #if defined( POLARSSL_HAVE_LONGLONG )
+           typedef unsigned long long t_udbl;
+           #define POLARSSL_HAVE_UDBL
+         #endif
+       #endif
+    #endif
   #endif
 #endif /* POLARSSL_HAVE_INT16 */
 #endif /* POLARSSL_HAVE_INT8  */
diff --git a/include/polarssl/config.h b/include/polarssl/config.h
index 4781d2c9df..c251eab705 100644
--- a/include/polarssl/config.h
+++ b/include/polarssl/config.h
@@ -61,14 +61,12 @@
  */
 
 /**
- * \def POLARSSL_HAVE_INT64
+ * \def POLARSSL_HAVE_LONGLONG
  *
- * The compiler supports the use of 64-bit types.
- * Code automatically enables on known working systems.
- *
- * Uncomment if the compiler supports 64-bit data types.
-#define POLARSSL_HAVE_INT64
+ * The compiler supports the 'long long' type.
+ * (Only used on 32-bit platforms)
  */
+#define POLARSSL_HAVE_LONGLONG
 
 /**
  * \def POLARSSL_HAVE_ASM
diff --git a/library/bignum.c b/library/bignum.c
index 60a8df42ec..0008748881 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1102,7 +1102,7 @@ int mpi_div_mpi( mpi *Q, mpi *R, const mpi *A, const mpi *B )
             Z.p[i - t - 1] = ~0;
         else
         {
-#if defined(POLARSSL_HAVE_INT64)
+#if defined(POLARSSL_HAVE_UDBL)
             t_udbl r;
 
             r  = (t_udbl) X.p[i] << biL;