diff --git a/math/randstr.go b/math/randstr.go
index d25a0cb..579ca66 100644
--- a/math/randstr.go
+++ b/math/randstr.go
@@ -3,12 +3,14 @@ package math
 import "strings"
 
 const (
-	alphabetic       = "abcdefghijklmnopqrstuvwxyz"
-	alphabeticLen    = len(alphabetic)
-	alphabeticMix    = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
-	alphabeticMixLen = len(alphabeticMix)
-	alphanumeric     = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
-	alphanumericLen  = len(alphanumeric)
+	alphabetic           = "abcdefghijklmnopqrstuvwxyz"
+	alphabeticLen        = len(alphabetic)
+	alphabeticMix        = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	alphabeticMixLen     = len(alphabeticMix)
+	alphanumeric         = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	alphanumericLen      = len(alphanumeric)
+	lowerAlphanumeric    = "abcdefghijklmnopqrstuvwxyz0123456789"
+	lowerAlphanumericLen = len(lowerAlphanumeric)
 )
 
 // RandLowerStr returns a truly random lowercase string of a specified length.
@@ -26,7 +28,7 @@ func RandUpperStr(l uint32) string {
 }
 
 // RandStr returns a truly random string of the specified length and the contents of
-// which are composed of upper and lowercase letters.
+// which are composed of uppercase and lowercase letters.
 func RandStr(l int) string {
 	s := make([]byte, l)
 	for i := range s {
@@ -44,3 +46,13 @@ func RandAlphanumeric(l int) string {
 	}
 	return string(s)
 }
+
+// RandLowerAlphanumeric returns a truly random string of the specified length and the contents of
+// which are composed of lowercase letters and numbers.
+func RandLowerAlphanumeric(l int) string {
+	s := make([]byte, l)
+	for i := range s {
+		s[i] = alphanumeric[RandIntn(lowerAlphanumericLen)]
+	}
+	return string(s)
+}
diff --git a/math/randstr_test.go b/math/randstr_test.go
index 7811d32..3ee3893 100644
--- a/math/randstr_test.go
+++ b/math/randstr_test.go
@@ -29,3 +29,9 @@ func TestRandAlphanumeric(t *testing.T) {
 	s := RandAlphanumeric(4)
 	assert.Equal(4, len(s))
 }
+
+func TestRandLowerAlphanumeric(t *testing.T) {
+	assert := internal.NewAssert(t, "TestRandLowerAlphanumeric")
+	s := RandLowerAlphanumeric(4)
+	assert.Equal(4, len(s))
+}