diff -u a/genfonts.py b/genfonts.py
--- a/genfonts.py	2020-06-07 18:23:07.934731665 +0300
+++ b/genfonts.py	2020-06-07 18:24:06.205790361 +0300
@@ -63,7 +63,7 @@
         try:
             font.generate(fontprefix+".ttf", flags=("opentype", "old-kern",
                     "PfEd-colors", "PfEd-lookups"))
-        except EnvironmentError, e:
+        except EnvironmentError as e:
             print("!!! %s" % e, file=sys.stderr)
             sys.exit(EX_GENFAIL)
     elif type == FT_CAD:
@@ -86,14 +86,14 @@
         try:
             font.generate(outfile, flags=("opentype", "old-kern",
                     "PfEd-colors", "PfEd-lookups"))
-        except EnvironmentError, e:
+        except EnvironmentError as e:
             print("!!! %s" % e, file=sys.stderr)
             sys.exit(EX_GENFAIL)
     else:
         try:
             font.generate(fontprefix+".otf", flags=("opentype", "PfEd-colors",
                     "PfEd-lookups"))
-        except EnvironmentError, e:
+        except EnvironmentError as e:
             print("!!! %s" % e, file=sys.stderr)
             sys.exit(EX_GENFAIL)