diff --git a/lib/scripts/legacy_lyxpreview2ppm.py b/lib/scripts/legacy_lyxpreview2ppm.py
index 63013dbe4c..ee49e6afa3 100644
--- a/lib/scripts/legacy_lyxpreview2ppm.py
+++ b/lib/scripts/legacy_lyxpreview2ppm.py
@@ -318,10 +318,13 @@ def legacy_conversion_step1(latex_file, dpi, output_format, fg_color, bg_color,
 def legacy_conversion_pdflatex(latex_file, failed_pages, legacy_metrics,
     use_pdftocairo, conv, gs_device, gs_ext, alpha, resolution, output_format):
 
+    error_count = 0
+
     # Search for pdflatex executable
     pdflatex = find_exe(["pdflatex"])
     if pdflatex == None:
         warning("Can't find pdflatex. Some pages failed with all the possible routes.")
+        failed_pages = []
     else:
         # Create a new LaTeX file from the original but only with failed pages
         pdf_latex_file = latex_file_re.sub("_pdflatex.tex", latex_file)
@@ -360,6 +363,7 @@ def legacy_conversion_pdflatex(latex_file, failed_pages, legacy_metrics,
         if conv_status:
             # Give up!
             warning("Some pages failed with all the possible routes")
+            failed_pages = []
         else:
             # We've done it!
             pdf_log_file = latex_file_re.sub(".log", pdf_latex_file)
@@ -370,6 +374,7 @@ def legacy_conversion_pdflatex(latex_file, failed_pages, legacy_metrics,
                 for index in error_pages:
                     pdf_metrics.pop(index - 1)
                     pdf_metrics.insert(index - 1, (index, -1.0))
+                    error_count += 1
 
             original_bitmap = latex_file_re.sub("%d." + output_format, pdf_latex_file)
             destination_bitmap = latex_file_re.sub("%d." + output_format, latex_file)
@@ -378,6 +383,8 @@ def legacy_conversion_pdflatex(latex_file, failed_pages, legacy_metrics,
             join_metrics_and_rename(legacy_metrics, pdf_metrics, failed_pages,
                 original_bitmap, destination_bitmap)
 
+    return error_count
+
 
 # The file has been processed through latex and we expect dvi output.
 # Run dvips, taking note whether it was successful.