diff --git a/src/ltc/prngs/fortuna.c b/src/ltc/prngs/fortuna.c
index b545617..400c732 100644
--- a/src/ltc/prngs/fortuna.c
+++ b/src/ltc/prngs/fortuna.c
@@ -72,11 +72,7 @@
 static ulong64 _fortuna_current_time(void)
 {
    ulong64 cur_time;
-#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L
-   struct timespec ts;
-   clock_gettime(CLOCK_MONOTONIC, &ts);
-   cur_time = (ulong64)(ts.tv_sec) * 1000000 + (ulong64)(ts.tv_nsec) / 1000; /* get microseconds */
-#elif defined(_WIN32)
+#if defined(_WIN32)
    FILETIME CurrentTime;
    ULARGE_INTEGER ul;
    GetSystemTimeAsFileTime(&CurrentTime);
@@ -85,6 +81,14 @@
    cur_time = ul.QuadPart; /* now we have 100ns intervals since 1 January 1601 */
    cur_time -= CONST64(116444736000000000); /* subtract 100ns intervals between 1601-1970 */
    cur_time /= 10; /* 100ns intervals > microseconds */
+#elif defined(LTC_CLOCK_GETTIME)
+  struct timespec ts;
+  clock_gettime(CLOCK_MONOTONIC, &ts);
+  cur_time = (ulong64)(ts.tv_sec) * 1000000 + (ulong64)(ts.tv_nsec) / 1000; /* get microseconds */
+#else
+  struct timeval tv;
+  gettimeofday(&tv, NULL);
+  cur_time = (ulong64)(tv.tv_sec) * 1000000 + (ulong64)(tv.tv_usec); /* get microseconds */
 #endif
    return cur_time / 100;
 }