diff --git a/core/src/net/sf/openrocket/appearance/defaults/ResourceDecalImage.java b/core/src/net/sf/openrocket/appearance/defaults/ResourceDecalImage.java
index 9bc7a4fbe..3e91342ea 100644
--- a/core/src/net/sf/openrocket/appearance/defaults/ResourceDecalImage.java
+++ b/core/src/net/sf/openrocket/appearance/defaults/ResourceDecalImage.java
@@ -50,14 +50,19 @@ public class ResourceDecalImage implements DecalImage {
 	
 	@Override
 	public void exportImage(File file) throws IOException {
-		InputStream is;
-		is = getBytes();
+		InputStream is = getBytes();
 		OutputStream os = new BufferedOutputStream(new FileOutputStream(file));
 
-		FileUtils.copy(is, os);
+		if (is == null) {
+			return;
+		}
 
-		is.close();
-		os.close();
+		try {
+			FileUtils.copy(is, os);
+		} finally {
+			is.close();
+			os.close();
+		}
 	}
 		
 	@Override
diff --git a/core/src/net/sf/openrocket/file/wavefrontobj/export/OBJExporterFactory.java b/core/src/net/sf/openrocket/file/wavefrontobj/export/OBJExporterFactory.java
index 14259bc81..6b24ce9b3 100644
--- a/core/src/net/sf/openrocket/file/wavefrontobj/export/OBJExporterFactory.java
+++ b/core/src/net/sf/openrocket/file/wavefrontobj/export/OBJExporterFactory.java
@@ -35,6 +35,8 @@ import net.sf.openrocket.rocketcomponent.RocketComponent;
 import net.sf.openrocket.rocketcomponent.Transition;
 import net.sf.openrocket.rocketcomponent.TubeFinSet;
 import net.sf.openrocket.util.FileUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.File;
 import java.io.FileOutputStream;
@@ -68,6 +70,8 @@ public class OBJExporterFactory {
     private final OBJExportOptions options;
     private final File file;
 
+    private static final Logger log = LoggerFactory.getLogger(OBJExporterFactory.class);
+
     // The different exporters for each component
     private static final Map<Class<? extends RocketComponent>, ExporterFactory<?>> EXPORTER_MAP = Map.of(
             BodyTube.class, (ExporterFactory<BodyTube>) BodyTubeExporter::new,
@@ -188,10 +192,14 @@ public class OBJExporterFactory {
             if (options.isExportAppearance()) {
                 String mtlFilePath = FileUtils.removeExtension(filePath) + ".mtl";
                 List<DefaultMtl> mtls = materials.get(obj);
-                try (OutputStream mtlOutputStream = new FileOutputStream(mtlFilePath, false)) {
-                    DefaultMtlWriter.write(mtls, mtlOutputStream);
-                } catch (IOException e) {
-                    throw new RuntimeException(e);
+                if (mtls != null) {
+                    try (OutputStream mtlOutputStream = new FileOutputStream(mtlFilePath, false)) {
+                        DefaultMtlWriter.write(mtls, mtlOutputStream);
+                    } catch (IOException e) {
+                        throw new RuntimeException(e);
+                    }
+                } else {
+                    log.debug("No materials to export for {}", filePath);
                 }
                 obj.setMtlFileNames(List.of(mtlFilePath));
             }