diff --git a/lib/qra/qracodes/normrnd.c b/lib/qra/qracodes/normrnd.c
index c14e3b3c1..90abfa425 100644
--- a/lib/qra/qracodes/normrnd.c
+++ b/lib/qra/qracodes/normrnd.c
@@ -30,18 +30,13 @@
 	// Windows (x64 and x86)
 	#include <windows.h>   // required only for GetTickCount(...)
 	#define K_RAND_MAX UINT_MAX
-#elif __unix__ // all unices, not all compilers
+#elif _SVID_SOURCE || _XOPEN_SOURCE || __unix__ || (defined (__APPLE__) && defined(__MACH__)) /* POSIX or Unix or Apple */
 	#include <stdlib.h>
 	#define rand_s(x) (*x)=(unsigned int)lrand48()	// returns unsigned integers in the range 0..0x7FFFFFFF
-	#define K_RAND_MAX 0x7FFFFFFF					// that's the max number generated by lrand48
-	// Unix
-#elif __linux__
-	#include <stdlib.h>
-	#define rand_s(x) (*x)=(unsigned int)lrand48()	// returns unsigned integers in the range 0..0x7FFFFFFF
-	#define K_RAND_MAX 0x7FFFFFFF					// that's the max number generated by lrand48
-	// linux
-#elif __APPLE__
-	// Mac OS, not sure if this is covered by __posix__ and/or __unix__ though...
+	#define K_RAND_MAX 0x7FFFFFFF					// that's the max number
+																				// generated by lrand48
+#else
+  #error "No good quality PRNG found"
 #endif