diff --git a/common/src/main/java/me/lucko/luckperms/common/api/ApiUtils.java b/common/src/main/java/me/lucko/luckperms/common/api/ApiUtils.java
index f09d1de2c..b8d849e7e 100644
--- a/common/src/main/java/me/lucko/luckperms/common/api/ApiUtils.java
+++ b/common/src/main/java/me/lucko/luckperms/common/api/ApiUtils.java
@@ -27,19 +27,24 @@ package me.lucko.luckperms.common.api;
 
 import com.google.common.base.Preconditions;
 
+import me.lucko.luckperms.common.config.ConfigKeys;
+import me.lucko.luckperms.common.plugin.LuckPermsPlugin;
 import me.lucko.luckperms.common.storage.misc.DataConstraints;
 
+import java.util.function.Predicate;
+
 public final class ApiUtils {
 
-    public static String checkUsername(String s) {
+    public static String checkUsername(String s, LuckPermsPlugin plugin) {
         if (s == null) {
             return null;
         }
 
-        Preconditions.checkArgument(
-                DataConstraints.PLAYER_USERNAME_TEST.test(s),
-                "Invalid username entry '" + s + "'. Usernames must be less than 16 chars and only contain 'a-z A-Z 1-9 _'."
-        );
+        Predicate<String> test = plugin.getConfiguration().get(ConfigKeys.ALLOW_INVALID_USERNAMES) ?
+                DataConstraints.PLAYER_USERNAME_TEST_LENIENT :
+                DataConstraints.PLAYER_USERNAME_TEST;
+
+        Preconditions.checkArgument(test.test(s), "Invalid username entry: " + s);
         return s;
     }
 
@@ -48,10 +53,7 @@ public final class ApiUtils {
             return null;
         }
 
-        Preconditions.checkArgument(
-                DataConstraints.GROUP_NAME_TEST.test(s),
-                "Invalid name entry '" + s + "'. Names must be less than 37 chars and only contain 'a-z A-Z 1-9'."
-        );
+        Preconditions.checkArgument(DataConstraints.GROUP_NAME_TEST.test(s), "Invalid name entry: " + s);
         return s.toLowerCase();
     }
 
diff --git a/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiLog.java b/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiLog.java
index c5fc522a2..a3993f11b 100644
--- a/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiLog.java
+++ b/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiLog.java
@@ -27,6 +27,7 @@ package me.lucko.luckperms.common.api.implementation;
 
 import me.lucko.luckperms.api.LogEntry;
 import me.lucko.luckperms.common.actionlog.Log;
+import me.lucko.luckperms.common.api.ApiUtils;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 
@@ -34,8 +35,6 @@ import java.util.Objects;
 import java.util.SortedSet;
 import java.util.UUID;
 
-import static me.lucko.luckperms.common.api.ApiUtils.checkName;
-
 @SuppressWarnings("unchecked")
 public class ApiLog implements me.lucko.luckperms.api.Log {
     private final Log handle;
@@ -64,12 +63,12 @@ public class ApiLog implements me.lucko.luckperms.api.Log {
     @Override
     public @NonNull SortedSet<LogEntry> getGroupHistory(@NonNull String name) {
         Objects.requireNonNull(name, "name");
-        return (SortedSet) this.handle.getGroupHistory(checkName(name));
+        return (SortedSet) this.handle.getGroupHistory(ApiUtils.checkName(name));
     }
 
     @Override
     public @NonNull SortedSet<LogEntry> getTrackHistory(@NonNull String name) {
         Objects.requireNonNull(name, "name");
-        return (SortedSet) this.handle.getTrackHistory(checkName(name));
+        return (SortedSet) this.handle.getTrackHistory(ApiUtils.checkName(name));
     }
 }
diff --git a/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiStorage.java b/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiStorage.java
index 3eeafa3fb..88db9f3f4 100644
--- a/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiStorage.java
+++ b/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiStorage.java
@@ -33,6 +33,7 @@ import me.lucko.luckperms.api.Track;
 import me.lucko.luckperms.api.User;
 import me.lucko.luckperms.api.event.cause.CreationCause;
 import me.lucko.luckperms.api.event.cause.DeletionCause;
+import me.lucko.luckperms.common.api.ApiUtils;
 import me.lucko.luckperms.common.bulkupdate.comparison.Constraint;
 import me.lucko.luckperms.common.bulkupdate.comparison.StandardComparison;
 import me.lucko.luckperms.common.node.factory.NodeFactory;
@@ -50,9 +51,6 @@ import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
 import java.util.function.Function;
 
-import static me.lucko.luckperms.common.api.ApiUtils.checkName;
-import static me.lucko.luckperms.common.api.ApiUtils.checkUsername;
-
 public class ApiStorage implements me.lucko.luckperms.api.Storage {
     private static final Function<Throwable, Boolean> CONSUME_EXCEPTION = throwable -> {
         throwable.printStackTrace();
@@ -114,7 +112,7 @@ public class ApiStorage implements me.lucko.luckperms.api.Storage {
     @Override
     public @NonNull CompletableFuture<Boolean> loadUser(@NonNull UUID uuid, String username) {
         Objects.requireNonNull(uuid, "uuid");
-        username = checkUsername(username);
+        username = ApiUtils.checkUsername(username, this.plugin);
 
         if (this.plugin.getUserManager().getIfLoaded(uuid) == null) {
             this.plugin.getUserManager().getHouseKeeper().registerApiUsage(uuid);
@@ -147,7 +145,7 @@ public class ApiStorage implements me.lucko.luckperms.api.Storage {
     @Override
     public @NonNull CompletableFuture<Boolean> createAndLoadGroup(@NonNull String name) {
         Objects.requireNonNull(name, "name");
-        return this.handle.createAndLoadGroup(checkName(name), CreationCause.API)
+        return this.handle.createAndLoadGroup(ApiUtils.checkName(name), CreationCause.API)
                 .thenApply(r -> true)
                 .exceptionally(consumeExceptionToFalse());
     }
@@ -155,7 +153,7 @@ public class ApiStorage implements me.lucko.luckperms.api.Storage {
     @Override
     public @NonNull CompletableFuture<Boolean> loadGroup(@NonNull String name) {
         Objects.requireNonNull(name, "name");
-        return this.handle.loadGroup(checkName(name))
+        return this.handle.loadGroup(ApiUtils.checkName(name))
                 .thenApply(Optional::isPresent)
                 .exceptionally(consumeExceptionToFalse());
     }
@@ -195,7 +193,7 @@ public class ApiStorage implements me.lucko.luckperms.api.Storage {
     @Override
     public @NonNull CompletableFuture<Boolean> createAndLoadTrack(@NonNull String name) {
         Objects.requireNonNull(name, "name");
-        return this.handle.createAndLoadTrack(checkName(name), CreationCause.API)
+        return this.handle.createAndLoadTrack(ApiUtils.checkName(name), CreationCause.API)
                 .thenApply(r -> true)
                 .exceptionally(consumeExceptionToFalse());
     }
@@ -203,7 +201,7 @@ public class ApiStorage implements me.lucko.luckperms.api.Storage {
     @Override
     public @NonNull CompletableFuture<Boolean> loadTrack(@NonNull String name) {
         Objects.requireNonNull(name, "name");
-        return this.handle.loadTrack(checkName(name))
+        return this.handle.loadTrack(ApiUtils.checkName(name))
                 .thenApply(Optional::isPresent)
                 .exceptionally(consumeExceptionToFalse());
     }
@@ -235,7 +233,7 @@ public class ApiStorage implements me.lucko.luckperms.api.Storage {
     public @NonNull CompletableFuture<Boolean> saveUUIDData(@NonNull String username, @NonNull UUID uuid) {
         Objects.requireNonNull(username, "username");
         Objects.requireNonNull(uuid, "uuid");
-        return this.handle.savePlayerData(uuid, checkUsername(username))
+        return this.handle.savePlayerData(uuid, ApiUtils.checkUsername(username, this.plugin))
                 .thenApply(r -> true)
                 .exceptionally(consumeExceptionToFalse());
     }
@@ -243,7 +241,7 @@ public class ApiStorage implements me.lucko.luckperms.api.Storage {
     @Override
     public @NonNull CompletableFuture<UUID> getUUID(@NonNull String username) {
         Objects.requireNonNull(username, "username");
-        return this.handle.getPlayerUuid(checkUsername(username));
+        return this.handle.getPlayerUuid(ApiUtils.checkUsername(username, this.plugin));
     }
 
     @Override
diff --git a/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiUserManager.java b/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiUserManager.java
index b5c59be6a..a30a62649 100644
--- a/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiUserManager.java
+++ b/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiUserManager.java
@@ -61,7 +61,7 @@ public class ApiUserManager extends ApiAbstractManager<User, me.lucko.luckperms.
     @Override
     public @NonNull CompletableFuture<me.lucko.luckperms.api.User> loadUser(@NonNull UUID uuid, @Nullable String username) {
         Objects.requireNonNull(uuid, "uuid");
-        ApiUtils.checkUsername(username);
+        ApiUtils.checkUsername(username, this.plugin);
 
         if (this.plugin.getUserManager().getIfLoaded(uuid) == null) {
             this.plugin.getUserManager().getHouseKeeper().registerApiUsage(uuid);