Check the argument, not the state.

diff --git a/src/main/java/net/pterodactylus/sone/data/Profile.java b/src/main/java/net/pterodactylus/sone/data/Profile.java
index 5a4fde0..4bf26cc 100644 (file)
--- a/src/main/java/net/pterodactylus/sone/data/Profile.java
+++ b/src/main/java/net/pterodactylus/sone/data/Profile.java
@@ -326,7 +326,7 @@ public class Profile implements Fingerprintable {
        public Field addField(String fieldName) throws IllegalArgumentException {
                checkNotNull(fieldName, "fieldName must not be null");
                checkArgument(fieldName.length() > 0, "fieldName must not be empty");
-               checkState(getFieldByName(fieldName) == null, "fieldName must be unique");
+               checkArgument(getFieldByName(fieldName) == null, "fieldName must be unique");
                @SuppressWarnings("synthetic-access")
                Field field = new Field().setName(fieldName);
                fields.add(field);