diff --git a/ocrmypdf/ghostscript.py b/ocrmypdf/ghostscript.py
index c043270d..0e3200d1 100644
--- a/ocrmypdf/ghostscript.py
+++ b/ocrmypdf/ghostscript.py
@@ -21,7 +21,7 @@ def rasterize_pdf(input_file, output_file, xres, yres, raster_device, log,
             '-dFirstPage=%i' % pageno,
             '-dLastPage=%i' % pageno,
             '-o', tmp.name,
-            '-r{0}x{1}'.format(str(xres), str(yres)),
+            '-r{0}x{1}'.format(str(round(xres)), str(round(yres))),
             input_file
         ]