diff --git a/src/crypto/tc/tomcrypt_cfg.h b/src/crypto/tc/tomcrypt_cfg.h
index 875207b..a7fadf3 100644
--- a/src/crypto/tc/tomcrypt_cfg.h
+++ b/src/crypto/tc/tomcrypt_cfg.h
@@ -197,10 +197,16 @@ LTC_EXPORT int   LTC_CALL XSTRCMP(const char *s1, const char *s2);
 /* ulong64: 64-bit data type */
 #ifdef _MSC_VER
    #define CONST64(n) n ## ui64
-   typedef unsigned __int64 ulong64;
+   #ifndef LTC_ULONG64
+     #define LTC_ULONG64
+     typedef unsigned __int64 ulong64;
+   #endif
 #else
    #define CONST64(n) n ## ULL
-   typedef unsigned long long ulong64;
+   #ifndef LTC_ULONG64
+     #define LTC_ULONG64
+     typedef unsigned long long ulong64;
+   #endif
 #endif
 
 /* ulong32: "32-bit at least" data type */
diff --git a/src/crypto/tfm/tfm.h b/src/crypto/tfm/tfm.h
index 700f4ee..49a4b2c 100644
--- a/src/crypto/tfm/tfm.h
+++ b/src/crypto/tfm/tfm.h
@@ -285,10 +285,16 @@
    /* this is to make porting into LibTomCrypt easier :-) */
 #ifndef CRYPT
    #if defined(_MSC_VER) || defined(__BORLANDC__)
-      typedef unsigned __int64   ulong64;
+      #ifndef LTC_ULONG64
+         #define LTC_ULONG64
+         typedef unsigned __int64   ulong64;
+      #endif
       typedef signed __int64     long64;
    #else
-      typedef unsigned long long ulong64;
+      #ifndef LTC_ULONG64
+         #define LTC_ULONG64
+         typedef unsigned long long ulong64;
+      #endif
       typedef signed long long   long64;
    #endif /* defined(_MSC_VER) ... */
 #endif /* CRYPT */