diff --git a/src/main/java/org/apache/maven/plugins/assembly/archive/DefaultAssemblyArchiver.java b/src/main/java/org/apache/maven/plugins/assembly/archive/DefaultAssemblyArchiver.java
index 9a39f997..a31b7e0e 100644
--- a/src/main/java/org/apache/maven/plugins/assembly/archive/DefaultAssemblyArchiver.java
+++ b/src/main/java/org/apache/maven/plugins/assembly/archive/DefaultAssemblyArchiver.java
@@ -325,13 +325,13 @@ protected Archiver createArchiver(
             archiver.setOverrideUid(configSource.getOverrideUid());
         }
         if (StringUtils.isNotBlank(configSource.getOverrideUserName())) {
-            archiver.setOverrideUserName(StringUtils.trim(configSource.getOverrideUserName()));
+            archiver.setOverrideUserName(configSource.getOverrideUserName() == null ? null : configSource.getOverrideUserName().trim());
         }
         if (configSource.getOverrideGid() != null) {
             archiver.setOverrideGid(configSource.getOverrideGid());
         }
         if (StringUtils.isNotBlank(configSource.getOverrideGroupName())) {
-            archiver.setOverrideGroupName(StringUtils.trim(configSource.getOverrideGroupName()));
+            archiver.setOverrideGroupName(configSource.getOverrideGroupName() == null ? null : configSource.getOverrideGroupName().trim());
         }
 
         return archiver;
diff --git a/src/main/java/org/apache/maven/plugins/assembly/utils/AssemblyFormatUtils.java b/src/main/java/org/apache/maven/plugins/assembly/utils/AssemblyFormatUtils.java
index 2d9b72a7..7caa8f16 100644
--- a/src/main/java/org/apache/maven/plugins/assembly/utils/AssemblyFormatUtils.java
+++ b/src/main/java/org/apache/maven/plugins/assembly/utils/AssemblyFormatUtils.java
@@ -346,8 +346,8 @@ public static String evaluateFileNameMapping(
 
         value = interpolator.interpolate(value);
 
-        value = StringUtils.replace(value, "//", "/");
-        value = StringUtils.replace(value, "\\\\", "\\");
+        value = value == null || value.isEmpty() ? value : value.replace("//", "/");
+        value = value == null || value.isEmpty() ? value : value.replace("\\\\", "\\");
         value = fixRelativeRefs(value);
 
         return value;
@@ -410,8 +410,8 @@ public static String getOutputDirectory(
             value = value.substring(1);
         }
 
-        value = StringUtils.replace(value, "//", "/");
-        value = StringUtils.replace(value, "\\\\", "\\");
+        value = value == null || value.isEmpty() ? value : value.replace("//", "/");
+        value = value == null || value.isEmpty() ? value : value.replace("\\\\", "\\");
         value = fixRelativeRefs(value);
 
         return value;