diff --git a/core/src/main/java/hudson/Functions.java b/core/src/main/java/hudson/Functions.java
index 8b4fbea69c..82e8b579c1 100644
--- a/core/src/main/java/hudson/Functions.java
+++ b/core/src/main/java/hudson/Functions.java
@@ -169,7 +169,6 @@ import java.util.concurrent.atomic.AtomicLong;
 import java.util.stream.Collectors;
 import edu.umd.cs.findbugs.annotations.CheckForNull;
 import edu.umd.cs.findbugs.annotations.NonNull;
-import org.apache.commons.io.IOUtils;
 import org.kohsuke.accmod.Restricted;
 import org.kohsuke.accmod.restrictions.NoExternalUse;
 import org.kohsuke.accmod.restrictions.DoNotUse;
@@ -1701,7 +1700,7 @@ public class Functions {
                 summary = summary.substring(0, summary.length() - suffix.length());
             }
         }
-        s.append(summary).append(IOUtils.LINE_SEPARATOR);
+        s.append(summary).append(System.lineSeparator());
         StackTraceElement[] trace = t.getStackTrace();
         int end = trace.length;
         if (higher != null) {
@@ -1715,7 +1714,7 @@ public class Functions {
             }
         }
         for (int i = 0; i < end; i++) {
-            s.append(prefix).append("\tat ").append(trace[i]).append(IOUtils.LINE_SEPARATOR);
+            s.append(prefix).append("\tat ").append(trace[i]).append(System.lineSeparator());
         }
     }
 
diff --git a/core/src/test/java/hudson/FunctionsTest.java b/core/src/test/java/hudson/FunctionsTest.java
index 5b74567cb9..c8365a1f78 100644
--- a/core/src/test/java/hudson/FunctionsTest.java
+++ b/core/src/test/java/hudson/FunctionsTest.java
@@ -43,7 +43,6 @@ import java.util.regex.Pattern;
 
 import hudson.util.VersionNumber;
 import jenkins.model.Jenkins;
-import org.apache.commons.io.IOUtils;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
@@ -555,10 +554,10 @@ public class FunctionsTest {
     private static void assertPrintThrowable(Throwable t, String traditional, String custom) {
         StringWriter sw = new StringWriter();
         t.printStackTrace(new PrintWriter(sw));
-        assertEquals(sw.toString().replace(IOUtils.LINE_SEPARATOR, "\n"), traditional);
+        assertEquals(sw.toString().replace(System.lineSeparator(), "\n"), traditional);
         String actual = Functions.printThrowable(t);
         System.out.println(actual);
-        assertEquals(actual.replace(IOUtils.LINE_SEPARATOR, "\n"), custom);
+        assertEquals(actual.replace(System.lineSeparator(), "\n"), custom);
     }
     private static final class Stack extends Throwable {
         private static final Pattern LINE = Pattern.compile("(.+)[.](.+)[.](.+):(\\d+)");