diff --git a/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/ContainerImageName.kt b/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/ContainerImageName.kt
index 307ad76..e119a87 100644
--- a/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/ContainerImageName.kt
+++ b/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/ContainerImageName.kt
@@ -44,7 +44,7 @@ class ContainerImageName(
         digest: Digest? = this.digest,
     ) = ContainerImageName(registry, repository, tag, digest)
 
-    override fun compareTo(other: ContainerImageName): Int = this.toString().compareTo(other.toString())
+    override fun compareTo(other: ContainerImageName): Int = toString().compareTo(other.toString())
 
     override fun equals(other: Any?): Boolean = when {
         this === other -> true
diff --git a/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Reference.kt b/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Reference.kt
index 8638347..a9382d8 100644
--- a/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Reference.kt
+++ b/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Reference.kt
@@ -39,7 +39,6 @@ class Digest(@JsonValue private val value: String) : Reference, Comparable<Diges
     override val separator: Char get() = Companion.separator
 
     override fun compareTo(other: Digest): Int = value.compareTo(other.value)
-
     override fun equals(other: Any?): Boolean = other is Digest && other.value == value
     override fun hashCode(): Int = value.hashCode()
     override fun toString(): String = value
diff --git a/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Registry.kt b/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Registry.kt
index 79996bf..000ed05 100644
--- a/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Registry.kt
+++ b/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Registry.kt
@@ -21,7 +21,7 @@ class Registry(@JsonValue private val value: String) : Comparable<Registry> {
         require(value.matches(regex)) { "invalid registry" }
     }
 
-    override fun compareTo(other: Registry): Int = value.compareTo(value)
+    override fun compareTo(other: Registry): Int = value.compareTo(other.value)
     override fun equals(other: Any?): Boolean = other is Registry && other.value == value
     override fun hashCode(): Int = value.hashCode()
     override fun toString(): String = value
diff --git a/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Repository.kt b/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Repository.kt
index 8877d8d..23432fe 100644
--- a/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Repository.kt
+++ b/kirc-image/src/main/kotlin/de/cmdjulian/kirc/image/Repository.kt
@@ -18,7 +18,7 @@ class Repository(@JsonValue private val value: String) : Comparable<Repository>
         is Digest -> ContainerImageName(repository = this, digest = reference)
     }
 
-    override fun compareTo(other: Repository): Int = value.compareTo(value)
+    override fun compareTo(other: Repository): Int = value.compareTo(other.value)
     override fun equals(other: Any?): Boolean = other is Repository && other.value == value
     override fun hashCode(): Int = value.hashCode()
     override fun toString(): String = value