diff --git a/tribune-core/src/main/kotlin/com/sksamuel/tribune/core/strings/lengths.kt b/tribune-core/src/main/kotlin/com/sksamuel/tribune/core/strings/lengths.kt
index 6ffdcb9..98eb7b6 100644
--- a/tribune-core/src/main/kotlin/com/sksamuel/tribune/core/strings/lengths.kt
+++ b/tribune-core/src/main/kotlin/com/sksamuel/tribune/core/strings/lengths.kt
@@ -1,5 +1,6 @@
 package com.sksamuel.tribune.core.strings
 
+import arrow.core.Either
 import arrow.core.leftNel
 import arrow.core.right
 import com.sksamuel.tribune.core.Parser
@@ -39,7 +40,28 @@ fun <I, E> Parser<I, String, E>.length(f: (Int) -> Boolean, ifError: (String) ->
    flatMap { if (f(it.length)) it.right() else ifError(it).leftNel() }
 
 /**
- * Narrows an existing String -> String [Parser] by enforcing a max length on the input string.
+ * Narrows an existing I -> String? [Parser] by enforcing a max length on the input string.
+ *
+ * For strings which have length longer than the given [len] arguments, an invalid is
+ * returned with the error message generated by [ifError].
+ *
+ * @param len the max length, inclusive
+ * @param ifError the error generating function
+ *
+ * @return valid if the input string is less than or equal to [len] or an invalid otherwise.
+ */
+@JvmName("maxlenOrNull")
+fun <I, E> Parser<I, String?, E>.maxlen(len: Int, ifError: (String) -> E): Parser<I, String?, E> =
+   flatMap {
+      when {
+         it == null -> Either.Right(null)
+         it.length > len -> ifError(it).leftNel()
+         else -> it.right()
+      }
+   }
+
+/**
+ * Narrows an existing I -> String? [Parser] by enforcing a max length on the input string.
  *
  * For strings which have length longer than the given [len] arguments, an invalid is
  * returned with the error message generated by [ifError].
@@ -59,7 +81,7 @@ fun <I, E> Parser<I, String, E>.maxlen(len: Int, ifError: (String) -> E): Parser
 
 
 /**
- * Narrows an existing String -> String [Parser] by enforcing a min length on the input string.
+ * Narrows an existing I -> String [Parser] by enforcing a min length on the input string.
  *
  * For strings which have length shorter than the given [len] arguments, an invalid is
  * returned with the error message generated by [ifError].
@@ -76,3 +98,24 @@ fun <I, E> Parser<I, String, E>.minlen(len: Int, ifError: (String) -> E): Parser
          else -> it.right()
       }
    }
+
+/**
+ * Narrows an existing I -> String? [Parser] by enforcing a min length on the input string.
+ *
+ * For strings which have length shorter than the given [len] arguments, an invalid is
+ * returned with the error message generated by [ifError].
+ *
+ * @param len the max length, inclusive
+ * @param ifError the error generating function
+ *
+ * @return valid if the input string is greater than or equal to [len] or an invalid otherwise.
+ */
+@JvmName("minlenOrNull")
+fun <I, E> Parser<I, String?, E>.minlen(len: Int, ifError: (String) -> E): Parser<I, String?, E> =
+   flatMap {
+      when {
+         it == null -> Either.Right(null)
+         it.length < len -> ifError(it).leftNel()
+         else -> it.right()
+      }
+   }
diff --git a/tribune-core/src/test/kotlin/com/sksamuel/tribune/core/strings.kt b/tribune-core/src/test/kotlin/com/sksamuel/tribune/core/strings.kt
index 5d6266d..70e2309 100644
--- a/tribune-core/src/test/kotlin/com/sksamuel/tribune/core/strings.kt
+++ b/tribune-core/src/test/kotlin/com/sksamuel/tribune/core/strings.kt
@@ -1,5 +1,6 @@
 package com.sksamuel.tribune.core
 
+import arrow.core.Either
 import arrow.core.leftNel
 import arrow.core.right
 import com.sksamuel.tribune.core.strings.length
@@ -35,11 +36,26 @@ class StringTest : FunSpec() {
          p.parse("abcd") shouldBe Foo("abcd").right()
       }
 
+      test("min length or null") {
+         val p = Parser<String?>().minlen(4) { "too short" }.mapIfNotNull { Foo(it) }
+         p.parse("abc") shouldBe "too short".leftNel()
+         p.parse("abcd") shouldBe Foo("abcd").right()
+         p.parse(null) shouldBe Either.Right(null)
+      }
+
       test("max length") {
-         val p = Parser<String>().maxlen(4) { "too long" }.map { Foo(it) }
+         val p = Parser<String>().maxlen(4) { "too long" }.notNull { "not null" }.map { Foo(it) }
+         p.parse("abcde") shouldBe "too long".leftNel()
+         p.parse("abcd") shouldBe Foo("abcd").right()
+         p.parse("abc") shouldBe Foo("abc").right()
+      }
+
+      test("max length on nullable string") {
+         val p = Parser<String?>().maxlen(4) { "too long" }.mapIfNotNull { Foo(it) }
          p.parse("abcde") shouldBe "too long".leftNel()
          p.parse("abcd") shouldBe Foo("abcd").right()
          p.parse("abc") shouldBe Foo("abc").right()
+         p.parse(null) shouldBe Either.Right(null)
       }
 
       test("length") {