diff --git a/node/utils/caching_middleware.js b/node/utils/caching_middleware.js
index e1d8677ea..809bb210f 100644
--- a/node/utils/caching_middleware.js
+++ b/node/utils/caching_middleware.js
@@ -146,7 +146,7 @@ CachingMiddleware.prototype = new function () {
         var statusCode = responseCache[cacheKey].statusCode;
 
         var pathStr = CACHE_DIR + 'minified_' + cacheKey;
-        if (supportsGzip) {
+        if (supportsGzip && (headers['content-type'] || '').match(/^text\//)) {
           pathStr = pathStr + '.gz';
           headers['content-encoding'] = 'gzip';
         }