1 files changed, 8 insertions, 8 deletions
diff --git a/lib/main.js b/lib/main.js
index f6e149f..54aeebb 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -13,22 +13,22 @@ function main(argv) {
     var outputDir = argv.output_dir;
     var outputFormat = argv.output_format;
     var styleMapPath = argv.style_map;
-    
+
     readStyleMap(styleMapPath).then(function(styleMap) {
         var options = {
             styleMap: styleMap,
             outputFormat: outputFormat
         };
-        
+
         if (outputDir) {
             var basename = path.basename(docxPath, ".docx");
             outputPath = path.join(outputDir, basename + ".html");
             var imageIndex = 0;
             options.convertImage = images.imgElement(function(element) {
                 imageIndex++;
-                var extension = element.contentType.split("/")[1];
-                var filename = imageIndex + "." + extension;
-                
+                var extension = images.imageFilenameExtension(element);
+                var filename = imageIndex + (extension === undefined ? "" : "." + extension);
+
                 return element.read().then(function(imageBuffer) {
                     var imagePath = path.join(outputDir, filename);
                     return promises.nfcall(fs.writeFile, imagePath, imageBuffer);
@@ -37,16 +37,16 @@ function main(argv) {
                 });
             });
         }
-        
+
         return mammoth.convert({path: docxPath}, options)
             .then(function(result) {
                 result.messages.forEach(function(message) {
                     process.stderr.write(message.message);
                     process.stderr.write("\n");
                 });
-                
+
                 var outputStream = outputPath ? fs.createWriteStream(outputPath) : process.stdout;
-                
+
                 outputStream.write(result.value);
             });
     }).done();