diff --git a/src/common/rand.c b/src/common/rand.c
new file mode 100644
index 00000000..c95d060a
--- /dev/null
+++ b/src/common/rand.c
@@ -0,0 +1,91 @@
+/* PRNG based on Mersenne Twister (M. Matsumoto and T. Nishimura, 1998). */
+
+#include "qcommon.h"
+
+#define RAND_M 397
+#define RAND_N 624
+#define MASK_U 0x80000000U
+#define MASK_L 0x7fffffffU
+#define MASK32 0xffffffffU
+
+rand_work_t rand_work;
+
+void
+ini_rand ( unsigned int u )
+{
+	int i;
+
+	rand_work.count = RAND_N;
+	rand_work.cnst [ 0 ] = 0;
+	rand_work.cnst [ 1 ] = 0x9908b0dfU;
+
+	u &= MASK32;
+	rand_work.vec [ 0 ] = u;
+
+	for ( i = 1; i < RAND_N; i++ )
+	{
+		u = i + 1812433253U * ( u ^ ( u >> 30 ) );
+		u &= MASK32;
+		rand_work.vec [ i ] = u;
+	}
+}
+
+int
+mtrand ( void )
+{
+	int u, u0, u1, u2;
+	int i;
+
+	if ( rand_work.count == RAND_N )
+	{
+		rand_work.count = 0;
+
+		for ( i = 0; i < RAND_N - RAND_M; i++ )
+		{
+			u = rand_work.vec [ i ] & MASK_U;
+			u |= rand_work.vec [ i + 1 ] & MASK_L;
+
+			u0 = rand_work.vec [ i + RAND_M ];
+			u1 = u >> 1;
+			u2 = rand_work.cnst [ u & 1 ];
+
+			rand_work.vec [ i ] = u0 ^ u1 ^ u2;
+		}
+
+		for ( ; i < RAND_N - 1; i++ )
+		{
+			u = rand_work.vec [ i ] & MASK_U;
+			u |= rand_work.vec [ i + 1 ] & MASK_L;
+
+			u0 = rand_work.vec [ i + RAND_M - RAND_N ];
+			u1 = u >> 1;
+			u2 = rand_work.cnst [ u & 1 ];
+
+			rand_work.vec [ i ] = u0 ^ u1 ^ u2;
+		}
+
+		u = rand_work.vec [ RAND_N - 1 ] & MASK_U;
+		u |= rand_work.vec [ 0 ] & MASK_L;
+
+		u0 = rand_work.vec [ RAND_M - 1 ];
+		u1 = u >> 1;
+		u2 = rand_work.cnst [ u & 1 ];
+
+		rand_work.vec [ RAND_N - 1 ] = u0 ^ u1 ^ u2;
+	}
+
+	u = rand_work.vec [ rand_work.count++ ];
+	u ^= ( u >> 11 );
+	u ^= ( u << 7 ) & 0x9d2c5680U;
+	u ^= ( u << 15 ) & 0xefc60000U;
+	u ^= ( u >> 18 );
+
+	if ( u < 0)
+	{
+		return ( ( u * -1 ) / 3 );
+	}
+	else
+	{
+		return ( u / 3 );
+	}
+}