diff --git a/pom.xml b/pom.xml
index fb3c039..614ede7 100644
--- a/pom.xml
+++ b/pom.xml
@@ -83,33 +83,25 @@
     </dependency>
 
     <!-- Test Dependencies -->
-    <dependency>
-      <groupId>org.assertj</groupId>
-      <artifactId>assertj-core</artifactId>
-      <version>${version.org.assertj}</version>
-      <scope>test</scope>
-    </dependency>
-
     <dependency>
       <groupId>org.junit.jupiter</groupId>
       <artifactId>junit-jupiter-api</artifactId>
       <version>${version.org.junit.jupiter}</version>
       <scope>test</scope>
     </dependency>
-
     <dependency>
       <groupId>org.junit.jupiter</groupId>
       <artifactId>junit-jupiter-engine</artifactId>
       <version>${version.org.junit.jupiter}</version>
       <scope>test</scope>
     </dependency>
-
     <dependency>
-      <groupId>com.squareup.okhttp3</groupId>
-      <artifactId>mockwebserver</artifactId>
-      <version>${version.com.squareup.okhttp3}</version>
+      <groupId>org.jetbrains.kotlin</groupId>
+      <artifactId>kotlin-test-junit5</artifactId>
+      <version>${version.kotlin}</version>
       <scope>test</scope>
     </dependency>
+
   </dependencies>
 
   <build>
diff --git a/src/main/kotlin/xyz/block/dap/DAP.kt b/src/main/kotlin/xyz/block/dap/DAP.kt
deleted file mode 100644
index 4e67bc7..0000000
--- a/src/main/kotlin/xyz/block/dap/DAP.kt
+++ /dev/null
@@ -1,10 +0,0 @@
-package xyz.block.dap
-
-data class DAP(
-    val handle: String,
-    val domain: String
-) {
-    override fun toString(): String {
-        return "@$handle/$domain'"
-    }
-}
diff --git a/src/main/kotlin/xyz/block/dap/Dap.kt b/src/main/kotlin/xyz/block/dap/Dap.kt
new file mode 100644
index 0000000..039e350
--- /dev/null
+++ b/src/main/kotlin/xyz/block/dap/Dap.kt
@@ -0,0 +1,34 @@
+package xyz.block.dap
+
+import java.util.regex.Pattern
+
+data class Dap(
+  val handle: String,
+  val domain: String
+) {
+  override fun toString(): String {
+    return "$PREFIX$handle$SEPARATOR$domain'"
+  }
+
+  companion object {
+    const val PREFIX = "@"
+    const val SEPARATOR = "/"
+
+    private const val DAP_REGEX = """^$PREFIX([^$PREFIX$SEPARATOR]+)$SEPARATOR([^$PREFIX$SEPARATOR]+)$"""
+    private val DAP_PATTERN = Pattern.compile(DAP_REGEX)
+
+    fun parse(dap: String): Dap {
+      val matcher = DAP_PATTERN.matcher(dap)
+      matcher.find()
+      if (!matcher.matches()) {
+        throw InvalidDapException
+      }
+      val handle = matcher.group(1)
+      val domain = matcher.group(2)
+
+      return Dap(handle, domain)
+    }
+  }
+}
+
+object InvalidDapException : Throwable(message = "Invalid DAP")
diff --git a/src/main/kotlin/xyz/block/maddr/MoneyAddress.kt b/src/main/kotlin/xyz/block/maddr/MoneyAddress.kt
index 6824e04..ce42ec4 100644
--- a/src/main/kotlin/xyz/block/maddr/MoneyAddress.kt
+++ b/src/main/kotlin/xyz/block/maddr/MoneyAddress.kt
@@ -1,14 +1,14 @@
 package xyz.block.maddr
 
 import xyz.block.maddr.MoneyAddress.Companion.KIND
-import xyz.block.maddr.urn.URN
+import xyz.block.maddr.urn.Urn
 
 // TODO(aparker) - placeholder, this should come from web5-kt
 data class DidService(val id: String, val type: String, val serviceEndpoints: List<String>)
 
 data class MoneyAddress(
   val id: String,
-  val urn: URN,
+  val urn: Urn,
   val currency: String,
   val css: String
 ) {
@@ -19,11 +19,11 @@ data class MoneyAddress(
 
 fun DidService.toMoneyAddresses(): List<MoneyAddress> {
   if (type != KIND) {
-    throw InvalidMoneyAddressException("invalid service type: $type")
+    throw InvalidMoneyAddressException
   }
 
   return serviceEndpoints.map { endpoint ->
-    val urn = URN.parse(endpoint)
+    val urn = Urn.parse(endpoint)
     MoneyAddress(
       id = id,
       urn = urn,
@@ -33,5 +33,4 @@ fun DidService.toMoneyAddresses(): List<MoneyAddress> {
   }
 }
 
-data class InvalidMoneyAddressException(val invalidValue: String) :
-  Throwable("Invalid MoneyAddress: $invalidValue")
+object InvalidMoneyAddressException : Throwable("Invalid MoneyAddress")
diff --git a/src/main/kotlin/xyz/block/maddr/urn/URN.kt b/src/main/kotlin/xyz/block/maddr/urn/URN.kt
deleted file mode 100644
index d562d52..0000000
--- a/src/main/kotlin/xyz/block/maddr/urn/URN.kt
+++ /dev/null
@@ -1,39 +0,0 @@
-package xyz.block.maddr.urn
-
-data class URN(
-  val nid: String,
-  val nss: String
-) {
-  private val urn: String = "$PREFIX$nid:$nss"
-
-  override fun toString(): String {
-    return urn
-  }
-
-  companion object {
-    const val PREFIX = "urn:"
-
-    fun parse(input: String): URN {
-      if (!input.startsWith(PREFIX)) {
-        throw InvalidUrnException("incorrect prefix", input)
-      }
-      val urnBody = input.substringAfter(PREFIX)
-      if (urnBody.isBlank()) {
-        throw InvalidUrnException("missing body", input)
-      }
-      val nid = urnBody.substringBefore(":")
-      val nss = urnBody.substringAfter(":")
-
-      if (nid.isBlank()) {
-        throw InvalidUrnException("missing nid", input)
-      }
-      if (nss.isBlank() || nss == urnBody) {
-        throw InvalidUrnException("missing nss", input)
-      }
-      return URN(nid, nss)
-    }
-  }
-}
-
-data class InvalidUrnException(val reason: String, val invalidValue: String) :
-  Throwable("Invalid URN: $reason: $invalidValue")
diff --git a/src/main/kotlin/xyz/block/maddr/urn/Urn.kt b/src/main/kotlin/xyz/block/maddr/urn/Urn.kt
new file mode 100644
index 0000000..8976b3b
--- /dev/null
+++ b/src/main/kotlin/xyz/block/maddr/urn/Urn.kt
@@ -0,0 +1,35 @@
+package xyz.block.maddr.urn
+
+import java.util.regex.Pattern
+
+data class Urn(
+  val nid: String,
+  val nss: String
+) {
+  private val urn: String = "$PREFIX$nid:$nss"
+
+  override fun toString(): String {
+    return urn
+  }
+
+  companion object {
+    const val PREFIX = "urn:"
+    private const val SEPARATOR = ":"
+
+    private val URN_PATTERN = Pattern.compile("""^${PREFIX}([^$SEPARATOR]+)$SEPARATOR(.+)$""")
+
+    fun parse(urn: String): Urn {
+      val matcher = URN_PATTERN.matcher(urn)
+      matcher.find()
+      if (!matcher.matches()) {
+        throw InvalidUrnException
+      }
+      val nid = matcher.group(1)
+      val nss = matcher.group(2)
+
+      return Urn(nid, nss)
+    }
+  }
+}
+
+object InvalidUrnException : Throwable("Invalid URN")
diff --git a/src/test/kotlin/xyz/block/dap/DAPTest.kt b/src/test/kotlin/xyz/block/dap/DAPTest.kt
deleted file mode 100644
index 1b8234a..0000000
--- a/src/test/kotlin/xyz/block/dap/DAPTest.kt
+++ /dev/null
@@ -1,13 +0,0 @@
-package xyz.block.dap
-
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Test
-
-class DAPTest {
-
-  @Test
-  fun testDapStringRepresentation() {
-    val dap = DAP("handle", "domain.com")
-    assertEquals("@handle/domain.com'", dap.toString())
-  }
-}
diff --git a/src/test/kotlin/xyz/block/dap/DapTest.kt b/src/test/kotlin/xyz/block/dap/DapTest.kt
new file mode 100644
index 0000000..2fd239a
--- /dev/null
+++ b/src/test/kotlin/xyz/block/dap/DapTest.kt
@@ -0,0 +1,42 @@
+package xyz.block.dap
+
+import org.junit.jupiter.api.assertThrows
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class DapTest {
+
+  @Test
+  fun testDapToString() {
+    val dap = Dap("handle", "domain.com")
+    assertEquals("@handle/domain.com'", dap.toString())
+  }
+
+  @Test
+  fun testParseDap() {
+    val dap = Dap.parse("@handle/domain.com")
+    assertEquals("handle", dap.handle)
+    assertEquals("domain.com", dap.domain)
+  }
+
+  @Test
+  fun testParseInvalidDaps() {
+    val invalidDaps = listOf(
+      "",
+      "a",
+      "@handle",
+      "@handle/",
+      "@handle@/domain.com",
+      "@handle//domain.com",
+      "@handle/@domain.com",
+      "@handle/domain.com@",
+      "@handle/domain.com/",
+    )
+    for (dap in invalidDaps) {
+      val exception = assertThrows<InvalidDapException> {
+        Dap.parse(dap)
+      }
+      assertEquals("Invalid DAP", exception.message)
+    }
+  }
+}
diff --git a/src/test/kotlin/xyz/block/maddr/MoneyAddressTest.kt b/src/test/kotlin/xyz/block/maddr/MoneyAddressTest.kt
index e3e2f4a..fc42d2c 100644
--- a/src/test/kotlin/xyz/block/maddr/MoneyAddressTest.kt
+++ b/src/test/kotlin/xyz/block/maddr/MoneyAddressTest.kt
@@ -1,11 +1,12 @@
 package xyz.block.maddr
 
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertThrows
-import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
 import xyz.block.maddr.urn.InvalidUrnException
+import kotlin.test.Test
+import kotlin.test.assertEquals
 
 class MoneyAddressTest {
+
   @Test
   fun testDidToMoneyAddress() {
     val did = DidService("didpay", "maddr", listOf("urn:nid:nss"))
@@ -59,7 +60,7 @@ class MoneyAddressTest {
 
   @Test
   fun testDidToMoneyAddressInvalidServiceType() {
-    assertThrows(InvalidMoneyAddressException::class.java) {
+    assertThrows<InvalidMoneyAddressException> {
       val did = DidService("didpay", "not-maddr", listOf("urn:nid:nss"))
       did.toMoneyAddresses()
     }
@@ -67,10 +68,9 @@ class MoneyAddressTest {
 
   @Test
   fun testDidToMoneyAddressInvalidUrn() {
-    assertThrows(InvalidUrnException::class.java) {
+    assertThrows<InvalidUrnException> {
       val did = DidService("didpay", "maddr", listOf("not-a-urn"))
       did.toMoneyAddresses()
     }
   }
 }
-
diff --git a/src/test/kotlin/xyz/block/maddr/urn/URNTest.kt b/src/test/kotlin/xyz/block/maddr/urn/URNTest.kt
deleted file mode 100644
index 1d432f1..0000000
--- a/src/test/kotlin/xyz/block/maddr/urn/URNTest.kt
+++ /dev/null
@@ -1,50 +0,0 @@
-package xyz.block.maddr.urn
-
-import org.junit.jupiter.api.Assertions.*
-import org.junit.jupiter.api.Test
-
-class URNTest {
-  @Test
-  fun testUrnParsing() {
-    val urn = URN.parse("urn:nid:nss")
-    assertEquals("urn:nid:nss", urn.toString())
-    assertEquals("nid", urn.nid)
-    assertEquals("nss", urn.nss)
-  }
-
-  @Test
-  fun testUrnParsingWithNssParts() {
-    val urn = URN.parse("urn:nid:nss1:nss2:nss3")
-    assertEquals("urn:nid:nss1:nss2:nss3", urn.toString())
-    assertEquals("nid", urn.nid)
-    assertEquals("nss1:nss2:nss3", urn.nss)
-  }
-
-  @Test
-  fun testUrnParsingInvalidPrefix()  {
-    assertThrows(InvalidUrnException::class.java) {
-      URN.parse("invalid:nid:nss")
-    }
-  }
-
-  @Test
-  fun testUrnParsingEmptyNss() {
-    assertThrows(InvalidUrnException::class.java) {
-      URN.parse("urn:nid:")
-    }
-  }
-
-  @Test
-  fun testUrnParsingMissingNss() {
-    assertThrows(InvalidUrnException::class.java) {
-      URN.parse("urn:nid")
-    }
-  }
-
-  @Test
-  fun testUrnParsingMissingNid() {
-    assertThrows(InvalidUrnException::class.java) {
-      URN.parse("uri:")
-    }
-  }
-}
\ No newline at end of file
diff --git a/src/test/kotlin/xyz/block/maddr/urn/UrnTest.kt b/src/test/kotlin/xyz/block/maddr/urn/UrnTest.kt
new file mode 100644
index 0000000..90c56cd
--- /dev/null
+++ b/src/test/kotlin/xyz/block/maddr/urn/UrnTest.kt
@@ -0,0 +1,43 @@
+package xyz.block.maddr.urn
+
+import org.junit.jupiter.api.assertThrows
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class UrnTest {
+
+  @Test
+  fun testUrnParsing() {
+    val urn = Urn.parse("urn:nid:nss")
+    assertEquals("urn:nid:nss", urn.toString())
+    assertEquals("nid", urn.nid)
+    assertEquals("nss", urn.nss)
+  }
+
+  @Test
+  fun testUrnParsingWithNssParts() {
+    val urn = Urn.parse("urn:nid:nss1:nss2:nss3")
+    assertEquals("urn:nid:nss1:nss2:nss3", urn.toString())
+    assertEquals("nid", urn.nid)
+    assertEquals("nss1:nss2:nss3", urn.nss)
+  }
+
+  @Test
+  fun testParseInvalidUrn() {
+    val invalidUrns = listOf(
+      "",
+      "invalid:nid:nss",
+      "invalid::nss",
+      "invalid:nid:",
+      "invalid:nid",
+      "invalid:",
+      "invalid::",
+    )
+    for (urn in invalidUrns) {
+      val exception = assertThrows<InvalidUrnException> {
+        Urn.parse(urn)
+      }
+      assertEquals("Invalid URN", exception.message)
+    }
+  }
+}