diff --git a/src/language/validation/names.ts b/src/language/validation/names.ts
index 503671100..1b5b98fb5 100644
--- a/src/language/validation/names.ts
+++ b/src/language/validation/names.ts
@@ -233,11 +233,14 @@ export const moduleMemberMustHaveNameThatIsUniqueInPackage = (services: SafeDsSe
             const packageName = getPackageName(member) ?? '';
 
             let declarationsInPackage: AstNodeDescription[];
+            let kind: string;
             if (packageName.startsWith(BUILTINS_ROOT_PACKAGE)) {
                 // For a builtin package the simple names of declarations must be unique
                 declarationsInPackage = packageManager.getDeclarationsInPackageOrSubpackage(BUILTINS_ROOT_PACKAGE);
+                kind = 'builtin declarations';
             } else {
                 declarationsInPackage = packageManager.getDeclarationsInPackage(packageName);
+                kind = 'declarations in this package';
             }
 
             if (
@@ -248,7 +251,7 @@ export const moduleMemberMustHaveNameThatIsUniqueInPackage = (services: SafeDsSe
                         !builtinUris.has(it.documentUri.toString()),
                 )
             ) {
-                accept('error', `Multiple declarations in this package have the name '${member.name}'.`, {
+                accept('error', `Multiple ${kind} have the name '${member.name}'.`, {
                     node: member,
                     property: 'name',
                     code: CODE_NAME_DUPLICATE,
diff --git a/tests/resources/validation/names/duplicates/across files/safeds 1.sdstest b/tests/resources/validation/names/duplicates/across files/safeds 1.sdstest
index 6b377dbb1..605fa9d5e 100644
--- a/tests/resources/validation/names/duplicates/across files/safeds 1.sdstest	
+++ b/tests/resources/validation/names/duplicates/across files/safeds 1.sdstest	
@@ -7,21 +7,21 @@ package safeds.lang
 // $TEST$ no error r"Multiple declarations in this package have the name '\w*'\."
 class »Any«
 
-// $TEST$ error "Multiple declarations in this package have the name 'DuplicateAnnotation'."
+// $TEST$ error "Multiple builtin declarations have the name 'DuplicateAnnotation'."
 annotation »DuplicateAnnotation«
-// $TEST$ error "Multiple declarations in this package have the name 'DuplicateClass'."
+// $TEST$ error "Multiple builtin declarations have the name 'DuplicateClass'."
 class »DuplicateClass«
-// $TEST$ error "Multiple declarations in this package have the name 'DuplicateEnum'."
+// $TEST$ error "Multiple builtin declarations have the name 'DuplicateEnum'."
 enum »DuplicateEnum«
-// $TEST$ error "Multiple declarations in this package have the name 'duplicateFunction'."
+// $TEST$ error "Multiple builtin declarations have the name 'duplicateFunction'."
 fun »duplicateFunction«()
-// $TEST$ no error r"Multiple declarations in this package have the name '\w*'\."
+// $TEST$ no error r"Multiple builtin declarations have the name '\w*'\."
 pipeline »duplicatePipeline« {}
-// $TEST$ error "Multiple declarations in this package have the name 'DuplicateSchema'."
+// $TEST$ error "Multiple builtin declarations have the name 'DuplicateSchema'."
 schema »DuplicateSchema« {}
-// $TEST$ error "Multiple declarations in this package have the name 'duplicatePublicSegment'."
+// $TEST$ error "Multiple builtin declarations have the name 'duplicatePublicSegment'."
 segment »duplicatePublicSegment«() {}
-// $TEST$ error "Multiple declarations in this package have the name 'duplicateInternalSegment'."
+// $TEST$ error "Multiple builtin declarations have the name 'duplicateInternalSegment'."
 internal segment »duplicateInternalSegment«() {}
-// $TEST$ no error r"Multiple declarations in this package have the name '\w*'\."
+// $TEST$ no error r"Multiple builtin declarations have the name '\w*'\."
 private segment »duplicatePrivateSegment«() {}
diff --git a/tests/resources/validation/names/duplicates/across files/safeds 2.sdstest b/tests/resources/validation/names/duplicates/across files/safeds 2.sdstest
index 5bf01fb1b..c0f4a34d0 100644
--- a/tests/resources/validation/names/duplicates/across files/safeds 2.sdstest	
+++ b/tests/resources/validation/names/duplicates/across files/safeds 2.sdstest	
@@ -1,20 +1,20 @@
 package safeds.lang.other
 
-// $TEST$ error "Multiple declarations in this package have the name 'DuplicateAnnotation'."
+// $TEST$ error "Multiple builtin declarations have the name 'DuplicateAnnotation'."
 annotation »DuplicateAnnotation«
-// $TEST$ error "Multiple declarations in this package have the name 'DuplicateClass'."
+// $TEST$ error "Multiple builtin declarations have the name 'DuplicateClass'."
 class »DuplicateClass«
-// $TEST$ error "Multiple declarations in this package have the name 'DuplicateEnum'."
+// $TEST$ error "Multiple builtin declarations have the name 'DuplicateEnum'."
 enum »DuplicateEnum«
-// $TEST$ error "Multiple declarations in this package have the name 'duplicateFunction'."
+// $TEST$ error "Multiple builtin declarations have the name 'duplicateFunction'."
 fun »duplicateFunction«()
-// $TEST$ no error r"Multiple declarations in this package have the name '\w*'\."
+// $TEST$ no error r"Multiple builtin declarations have the name '\w*'\."
 pipeline »duplicatePipeline« {}
-// $TEST$ error "Multiple declarations in this package have the name 'DuplicateSchema'."
+// $TEST$ error "Multiple builtin declarations have the name 'DuplicateSchema'."
 schema »DuplicateSchema« {}
-// $TEST$ error "Multiple declarations in this package have the name 'duplicatePublicSegment'."
+// $TEST$ error "Multiple builtin declarations have the name 'duplicatePublicSegment'."
 segment »duplicatePublicSegment«() {}
-// $TEST$ error "Multiple declarations in this package have the name 'duplicateInternalSegment'."
+// $TEST$ error "Multiple builtin declarations have the name 'duplicateInternalSegment'."
 internal segment »duplicateInternalSegment«() {}
-// $TEST$ no error r"Multiple declarations in this package have the name '\w*'\."
+// $TEST$ no error r"Multiple builtin declarations have the name '\w*'\."
 private segment »duplicatePrivateSegment«() {}