diff --git a/src/img2pdf.py b/src/img2pdf.py
index fa5f40d..a97e5c2 100755
--- a/src/img2pdf.py
+++ b/src/img2pdf.py
@@ -744,19 +744,19 @@ def read_images(rawdata, colorspace, first_frame_only=False):
 
 # converts a length in pixels to a length in PDF units (1/72 of an inch)
 def px_to_pt(length, dpi):
-    return 72*length/dpi
+    return 72.0*length/dpi
 
 
 def cm_to_pt(length):
-    return (72*length)/2.54
+    return (72.0*length)/2.54
 
 
 def mm_to_pt(length):
-    return (72*length)/25.4
+    return (72.0*length)/25.4
 
 
 def in_to_pt(length):
-    return 72*length
+    return 72.0*length
 
 
 def get_layout_fun(pagesize=None, imgsize=None, border=None, fit=None,
diff --git a/src/tests/__init__.py b/src/tests/__init__.py
index caa201b..e6f3508 100644
--- a/src/tests/__init__.py
+++ b/src/tests/__init__.py
@@ -513,8 +513,8 @@ def test_suite():
                 # Search online for the 72.009 dpi problem for more info.
                 ndpi = (int(round(ndpi[0])), int(round(ndpi[1])))
                 imgwidthpx, imgheightpx = orig_img.size
-                pagewidth = 72*imgwidthpx/ndpi[0]
-                pageheight = 72*imgheightpx/ndpi[1]
+                pagewidth = 72.0*imgwidthpx/ndpi[0]
+                pageheight = 72.0*imgheightpx/ndpi[1]
 
                 def format_float(f):
                     if int(f) == f: