diff --git a/deprecated/alfresco-transformer-base/src/test/java/org/alfresco/transformer/AbstractMetadataExtractsIT.java b/deprecated/alfresco-transformer-base/src/test/java/org/alfresco/transformer/AbstractMetadataExtractsIT.java
index 2a163f89..25e0f833 100644
--- a/deprecated/alfresco-transformer-base/src/test/java/org/alfresco/transformer/AbstractMetadataExtractsIT.java
+++ b/deprecated/alfresco-transformer-base/src/test/java/org/alfresco/transformer/AbstractMetadataExtractsIT.java
@@ -39,6 +39,7 @@ import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.Serializable;
+import java.nio.file.Files;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -101,7 +102,8 @@ public abstract class AbstractMetadataExtractsIT
 
             String metadataFilename = sourceFile + "_metadata.json";
             Map<String, Serializable> actualMetadata = readMetadata(response.getBody().getInputStream());
-            File actualMetadataFile = new File(metadataFilename);
+            File actualMetadataFile = Files.createTempFile(
+                    "actual-" + new File(sourceFile).getName() + "-", ".json").toFile();
             jsonObjectMapper.writerWithDefaultPrettyPrinter().writeValue(actualMetadataFile, actualMetadata);
 
             Map<String, Serializable> expectedMetadata = readExpectedMetadata(metadataFilename, actualMetadataFile);
diff --git a/engines/base/src/main/java/org/alfresco/transform/base/executors/RuntimeExec.java b/engines/base/src/main/java/org/alfresco/transform/base/executors/RuntimeExec.java
index 672ba677..1ee77ba6 100644
--- a/engines/base/src/main/java/org/alfresco/transform/base/executors/RuntimeExec.java
+++ b/engines/base/src/main/java/org/alfresco/transform/base/executors/RuntimeExec.java
@@ -666,11 +666,11 @@ public class RuntimeExec
             for (Map.Entry<String, String> entry : execProperties.entrySet())
             {
                 String key = entry.getKey();
-                String value = entry.getValue();
-                // ignore null
-                if (value == null)
+                String value = entry.getValue() == null ? "" : entry.getValue();
+                if (value.contains("\n") || value.contains("\r") || value.contains("\0"))
                 {
-                    value = "";
+                    throw new IllegalArgumentException(
+                            "Command property '" + key + "' contains an illegal character");
                 }
                 // progressively replace the property in the command
                 key = (VAR_OPEN + key + VAR_CLOSE);
diff --git a/engines/base/src/test/java/org/alfresco/transform/base/metadata/AbstractMetadataExtractsIT.java b/engines/base/src/test/java/org/alfresco/transform/base/metadata/AbstractMetadataExtractsIT.java
index bd657081..e1e93ae5 100644
--- a/engines/base/src/test/java/org/alfresco/transform/base/metadata/AbstractMetadataExtractsIT.java
+++ b/engines/base/src/test/java/org/alfresco/transform/base/metadata/AbstractMetadataExtractsIT.java
@@ -39,6 +39,7 @@ import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.Serializable;
+import java.nio.file.Files;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -100,7 +101,8 @@ public abstract class AbstractMetadataExtractsIT
 
             String metadataFilename = sourceFile + "_metadata.json";
             Map<String, Serializable> actualMetadata = readMetadata(response.getBody().getInputStream());
-            File actualMetadataFile = new File(metadataFilename);
+            File actualMetadataFile = Files.createTempFile(
+                    "actual-" + new File(sourceFile).getName() + "-", ".json").toFile();
             jsonObjectMapper.writerWithDefaultPrettyPrinter().writeValue(actualMetadataFile, actualMetadata);
 
             Map<String, Serializable> expectedMetadata = readExpectedMetadata(metadataFilename, actualMetadataFile);