diff --git a/src/test/java/org/jpeek/MetricsTest.java b/src/test/java/org/jpeek/MetricsTest.java
index cea86c38..6bd14c13 100644
--- a/src/test/java/org/jpeek/MetricsTest.java
+++ b/src/test/java/org/jpeek/MetricsTest.java
@@ -28,6 +28,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Collection;
+import java.util.Locale;
 import org.cactoos.collection.CollectionOf;
 import org.cactoos.text.TextOf;
 import org.hamcrest.MatcherAssert;
@@ -223,6 +224,7 @@ public void testsTarget() throws IOException {
             ),
             XhtmlMatchers.hasXPaths(
                 String.format(
+                    Locale.US,
                     xpath,
                     this.target, this.value
                 )