diff --git a/libs/model/src/main/kotlin/de/cyface/model/osm/MapTag.kt b/libs/model/src/main/kotlin/de/cyface/model/osm/MapTag.kt
index e85d384..75d388e 100644
--- a/libs/model/src/main/kotlin/de/cyface/model/osm/MapTag.kt
+++ b/libs/model/src/main/kotlin/de/cyface/model/osm/MapTag.kt
@@ -18,7 +18,6 @@
  */
 package de.cyface.model.osm
 
-import org.apache.commons.lang3.Validate
 import java.util.Objects
 
 /**
@@ -27,14 +26,7 @@ import java.util.Objects
  * @author Armin Schnabel
  * @property key The key of the OSM attribute
  */
-abstract class MapTag(key: String) {
-    @JvmField
-    val key: String
-
-    init {
-        Validate.notNull(key)
-        this.key = key
-    }
+abstract class MapTag(val key: String) {
 
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
diff --git a/libs/model/src/main/kotlin/de/cyface/model/osm/OsmTag.kt b/libs/model/src/main/kotlin/de/cyface/model/osm/OsmTag.kt
index 5185e65..52d2432 100644
--- a/libs/model/src/main/kotlin/de/cyface/model/osm/OsmTag.kt
+++ b/libs/model/src/main/kotlin/de/cyface/model/osm/OsmTag.kt
@@ -18,8 +18,6 @@
  */
 package de.cyface.model.osm
 
-import org.apache.commons.lang3.Validate
-
 /**
  * Represents a single key,value paired Open Street Map (OSM) attribute.
  *
@@ -28,9 +26,12 @@ import org.apache.commons.lang3.Validate
  * @property value The value of the OSM attribute
  */
 class OsmTag(key: String?, val value: Any) : MapTag(key!!) {
+
+    // Before other types were injected by accident, like `TextNode`
     init {
-        // Before other types were injected by accident, like `TextNode`
-        Validate.isTrue(value is String || value is Double || value is Int)
+        require(value is String || value is Double || value is Int) {
+            "Invalid value type for OsmTag: ${value::class}"
+        }
     }
 
     override fun equals(other: Any?): Boolean {
@@ -42,9 +43,7 @@ class OsmTag(key: String?, val value: Any) : MapTag(key!!) {
     }
 
     override fun hashCode(): Int {
-        var result = super.hashCode()
-        result = 31 * result + value.hashCode()
-        return result
+        return 31 * super.hashCode() + value.hashCode()
     }
 
     override fun toString(): String {