--- a/sys/libkern/random.c
+++ b/sys/libkern/random.c
@@ -32,6 +32,7 @@
  */
 
 #include <sys/libkern.h>
+#include <machine/atomic.h>
 
 static u_long randseed = 1;
 
@@ -49,7 +50,8 @@
 u_long
 krandom(void)
 {
-	long x, hi, lo, t;
+	u_long x;
+	long hi, lo, t;
 
 	/*
 	 * Compute x[n + 1] = (7^5 * x[n]) mod (2^31 - 1).
@@ -57,12 +59,13 @@
 	 * Park and Miller, Communications of the ACM, vol. 31, no. 10,
 	 * October 1988, p. 1195.
 	 */
-	x = randseed;
-	hi = x / 127773;
-	lo = x % 127773;
-	t = 16807 * lo - 2836 * hi;
-	if (t <= 0)
-		t += 0x7fffffff;
-	randseed = t;
+	do {
+		x = randseed;
+		hi = x / 127773;
+		lo = x % 127773;
+		t = 16807 * lo - 2836 * hi;
+		if (t <= 0)
+			t += 0x7fffffff;
+	} while (atomic_cmpset_long(&randseed, x, (u_long)t) == 0);
 	return (t);
 }