diff --git a/common/random.go b/common/random.go
index 186fb2a40..6e92d96df 100644
--- a/common/random.go
+++ b/common/random.go
@@ -1,12 +1,33 @@
 package common
 
-import "crypto/rand"
+import (
+	"math/rand"
+)
 
+const (
+	strChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" // 62 characters
+)
+
+// Construts an alphanumeric string of given length.
 func RandStr(length int) string {
-	b := make([]byte, length)
-	_, err := rand.Read(b)
-	if err != nil {
-		return ""
+	chars := []byte{}
+MAIN_LOOP:
+	for {
+		val := rand.Int63()
+		for i := 0; i < 10; i++ {
+			v := int(val & 0x3f) // rightmost 6 bits
+			if v >= 62 {         // only 62 characters in strChars
+				val >>= 6
+				continue
+			} else {
+				chars = append(chars, strChars[v])
+				if len(chars) == length {
+					break MAIN_LOOP
+				}
+				val >>= 6
+			}
+		}
 	}
-	return string(b)
+
+	return string(chars)
 }