diff --git a/thumbnail/djvucreator.cpp b/thumbnail/djvucreator.cpp
--- a/thumbnail/djvucreator.cpp
+++ b/thumbnail/djvucreator.cpp
@@ -37,7 +37,7 @@
 
 #include <QFile>
 #include <QImage>
-
+#include <QStandardPaths>
 
 extern "C"
 {
@@ -49,6 +49,9 @@
 
 bool DjVuCreator::create(const QString &path, int width, int height, QImage &img)
 {
+  if (QStandardPaths::findExecutable(QStringLiteral("ddjvu")).isEmpty())
+     return false;
+
   int output[2];
   QByteArray data(1024, 'k');
   bool ok = false;
@@ -71,13 +74,15 @@
   pid_t pid = fork(); 
   if (pid == 0)
     {
+      // child process
       close(output[0]);
       dup2(output[1], STDOUT_FILENO);	  
       execvp(argv[0], const_cast<char *const *>(argv));
-      exit(1);
+      _exit(1);
     }
-  else if (pid >= 0)
+  else if (pid > 0)
     {
+      // parent process
       close(output[1]);
       int offset = 0;
       while (!ok) {
@@ -116,6 +121,7 @@
     }
   else
     {
+      // error case
       close(output[1]);
     }