diff --git a/masks.go b/masks.go
new file mode 100644
index 0000000..610ae4d
--- /dev/null
+++ b/masks.go
@@ -0,0 +1,12 @@
+package primality
+
+// MaskOfEratosthenes uses a bitmask produced by a modified sieve of
+// Eratosthenes in order to compare the desired integer against the
+// corresponding index in the mask
+func MaskOfEratosthenes(n int) bool {
+	if n < 2 || ((n > 2) && n&1 == 0) {
+		return false
+	}
+	bz := SieveOfEratosthenes(uint64(n))
+	return bz[n] != 0
+}