Index: src/Plugins/Pdf/pdf_hummus_renderer.cpp
===================================================================
--- src/Plugins/Pdf/pdf_hummus_renderer.cpp	(revision 7794)
+++ src/Plugins/Pdf/pdf_hummus_renderer.cpp	(working copy)
@@ -1300,6 +1300,9 @@
       system (cmd, name, temp);
     } else if ( s != "ps" && s != "eps") {
       // generic image format : use convert from ImageMagik
+      if (!exists_in_path ("convert"))
+        cerr << "PDF export error: ImageMagick required for conversion from format "
+        << s << LF;
       string cmd= "convert";
       system (cmd, name, temp);
     } else {