diff --git a/bundles/org.openhab.binding.denonmarantz/src/main/java/org/openhab/binding/denonmarantz/internal/connector/telnet/DenonMarantzTelnetConnector.java b/bundles/org.openhab.binding.denonmarantz/src/main/java/org/openhab/binding/denonmarantz/internal/connector/telnet/DenonMarantzTelnetConnector.java
index 589c87ee2..2d1a14b82 100644
--- a/bundles/org.openhab.binding.denonmarantz/src/main/java/org/openhab/binding/denonmarantz/internal/connector/telnet/DenonMarantzTelnetConnector.java
+++ b/bundles/org.openhab.binding.denonmarantz/src/main/java/org/openhab/binding/denonmarantz/internal/connector/telnet/DenonMarantzTelnetConnector.java
@@ -20,7 +20,6 @@ import java.util.concurrent.Future;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.regex.Pattern;
 
-import org.apache.commons.lang3.StringUtils;
 import org.openhab.binding.denonmarantz.internal.DenonMarantzState;
 import org.openhab.binding.denonmarantz.internal.config.DenonMarantzConfiguration;
 import org.openhab.binding.denonmarantz.internal.connector.DenonMarantzConnector;
@@ -166,7 +165,7 @@ public class DenonMarantzTelnetConnector extends DenonMarantzConnector implement
                     state.setSurroundProgram(value);
                     break;
                 case "MV": // Main zone volume
-                    if (StringUtils.isNumeric(value)) {
+                    if (value.chars().allMatch(Character::isDigit)) {
                         state.setMainVolume(fromDenonValue(value));
                     }
                     break;
@@ -183,7 +182,7 @@ public class DenonMarantzTelnetConnector extends DenonMarantzConnector implement
                         state.setZone2Power(value.equals("ON"));
                     } else if (value.equals("MUON") || value.equals("MUOFF")) {
                         state.setZone2Mute(value.equals("MUON"));
-                    } else if (StringUtils.isNumeric(value)) {
+                    } else if (value.chars().allMatch(Character::isDigit)) {
                         state.setZone2Volume(fromDenonValue(value));
                     } else {
                         state.setZone2Input(value);
@@ -194,7 +193,7 @@ public class DenonMarantzTelnetConnector extends DenonMarantzConnector implement
                         state.setZone3Power(value.equals("ON"));
                     } else if (value.equals("MUON") || value.equals("MUOFF")) {
                         state.setZone3Mute(value.equals("MUON"));
-                    } else if (StringUtils.isNumeric(value)) {
+                    } else if (value.chars().allMatch(Character::isDigit)) {
                         state.setZone3Volume(fromDenonValue(value));
                     } else {
                         state.setZone3Input(value);
@@ -205,7 +204,7 @@ public class DenonMarantzTelnetConnector extends DenonMarantzConnector implement
                         state.setZone4Power(value.equals("ON"));
                     } else if (value.equals("MUON") || value.equals("MUOFF")) {
                         state.setZone4Mute(value.equals("MUON"));
-                    } else if (StringUtils.isNumeric(value)) {
+                    } else if (value.chars().allMatch(Character::isDigit)) {
                         state.setZone4Volume(fromDenonValue(value));
                     } else {
                         state.setZone4Input(value);
diff --git a/bundles/org.openhab.binding.denonmarantz/src/main/java/org/openhab/binding/denonmarantz/internal/xml/adapters/StringAdapter.java b/bundles/org.openhab.binding.denonmarantz/src/main/java/org/openhab/binding/denonmarantz/internal/xml/adapters/StringAdapter.java
index 25a5dc88a..24255eaba 100644
--- a/bundles/org.openhab.binding.denonmarantz/src/main/java/org/openhab/binding/denonmarantz/internal/xml/adapters/StringAdapter.java
+++ b/bundles/org.openhab.binding.denonmarantz/src/main/java/org/openhab/binding/denonmarantz/internal/xml/adapters/StringAdapter.java
@@ -14,8 +14,6 @@ package org.openhab.binding.denonmarantz.internal.xml.adapters;
 
 import javax.xml.bind.annotation.adapters.XmlAdapter;
 
-import org.apache.commons.lang3.StringUtils;
-
 /**
  * Adapter to clean up string values
  *
@@ -27,7 +25,7 @@ public class StringAdapter extends XmlAdapter<String, String> {
     public String unmarshal(String v) throws Exception {
         String val = v;
         if (val != null) {
-            val = StringUtils.trimToEmpty(val);
+            return val.trim();
         }
         return val;
     }