diff --git a/config/core/src/main/java/org/apache/karaf/config/core/impl/KarafConfigurationPlugin.java b/config/core/src/main/java/org/apache/karaf/config/core/impl/KarafConfigurationPlugin.java
index 56261ca0e41..27099a0fd33 100644
--- a/config/core/src/main/java/org/apache/karaf/config/core/impl/KarafConfigurationPlugin.java
+++ b/config/core/src/main/java/org/apache/karaf/config/core/impl/KarafConfigurationPlugin.java
@@ -48,10 +48,9 @@ public void modifyConfiguration(ServiceReference<?> reference, Dictionary<String
                     properties.put(key, values);
                 } else {
                     value = InterpolationHelper.substVars(value, null,null, convertDictionaryToMap(properties));
-                    try {
-                        int intValue = Integer.parseInt(value);
-                        properties.put(key, intValue);
-                    } catch (NumberFormatException e) {
+                    if (properties.get(key) != null && (properties.get(key) instanceof Number)) {
+                        properties.put(key, Integer.parseInt(value));
+                    } else {
                         properties.put(key, value);
                     }
                 }
@@ -66,14 +65,12 @@ public void modifyConfiguration(ServiceReference<?> reference, Dictionary<String
                     properties.put(key, values);
                 } else {
                     value = InterpolationHelper.substVars(value, null,null, convertDictionaryToMap(properties));
-                    try {
-                        int intValue = Integer.parseInt(value);
-                        properties.put(key, intValue);
-                    } catch (NumberFormatException e) {
+                    if (properties.get(key) != null && (properties.get(key) instanceof Number)) {
+                        properties.put(key, Integer.parseInt(value));
+                    } else {
                         properties.put(key, value);
                     }
                 }
-
             }
         }
     }
diff --git a/config/core/src/test/java/org/apache/karaf/config/core/impl/KarafConfigurationPluginTest.java b/config/core/src/test/java/org/apache/karaf/config/core/impl/KarafConfigurationPluginTest.java
index cd2a138b7bc..3a0c158a57a 100644
--- a/config/core/src/test/java/org/apache/karaf/config/core/impl/KarafConfigurationPluginTest.java
+++ b/config/core/src/test/java/org/apache/karaf/config/core/impl/KarafConfigurationPluginTest.java
@@ -28,14 +28,19 @@ public class KarafConfigurationPluginTest {
     @Test
     public void testSystemProperty() throws Exception {
         System.setProperty("org.apache.karaf.shell.sshPort", "8102");
+        System.setProperty("org.apache.karaf.shell.sshPorts", "[8102,8103]");
         KarafConfigurationPlugin plugin = new KarafConfigurationPlugin();
         Dictionary<String, Object> properties = new Hashtable<>();
         properties.put(Constants.SERVICE_PID, "org.apache.karaf.shell");
         properties.put("foo", "bar");
         properties.put("sshPort", 8101);
+        properties.put("sshPorts", new String[] { "8102" });
         plugin.modifyConfiguration(null, properties);
 
         Assert.assertEquals(8102, properties.get("sshPort"));
+        Assert.assertEquals(2, ((String[])properties.get("sshPorts")).length);
+        Assert.assertEquals("8102", ((String[])properties.get("sshPorts"))[0]);
+        Assert.assertEquals("8103", ((String[])properties.get("sshPorts"))[1]);
         Assert.assertEquals("bar", properties.get("foo"));
     }