diff --git a/lib/generators/ebook.js b/lib/generators/ebook.js
index b63c6b0a8..e9ca20cae 100644
--- a/lib/generators/ebook.js
+++ b/lib/generators/ebook.js
@@ -102,9 +102,8 @@ Generator.prototype.finish = function() {
         ].join(" ");
 
         that.book.log.info("start conversion to", that.ebookFormat, "....");
-        exec(command, function (error, stdout, stderr) {
-            if (stdout) that.book.log.debug.ln(stdout);
-            if (stderr) that.book.log.debug.ln(stderr);
+
+        var child = exec(command, function (error, stdout, stderr) {
             if (error) {
                 that.book.log.info.fail();
 
@@ -120,6 +119,14 @@ Generator.prototype.finish = function() {
             d.resolve();
         });
 
+        child.stdout.on('data', function (data) {
+            that.book.log.debug(data);
+        });
+
+        child.stderr.on('data', function (data) {
+            that.book.log.debug(data);
+        });
+
         return d.promise;
     });
 };