pygost/asn1schemas/cert-selfsigned-example.py | 2 +-

diff --git a/pygost/asn1schemas/cert-selfsigned-example.py b/pygost/asn1schemas/cert-selfsigned-example.py
index 9de0f0e11dca16b127ead844dcd266fa193314259c63e6b2dfb85a807101175b..f24602bff687475a05a630b9d4e62ab4a0754dda6734f56bb60b7d0731a646b6 100644
--- a/pygost/asn1schemas/cert-selfsigned-example.py
+++ b/pygost/asn1schemas/cert-selfsigned-example.py
@@ -54,7 +54,7 @@     sys_exit("Usage: cert-selfsigned-example.py COMMON-NAME")
 
 
 def pem(obj):
-    return fill(standard_b64encode(obj.encode()).decode('ascii'), 64)
+    return fill(standard_b64encode(obj.encode()).decode("ascii"), 64)
 
 
 key_params = GostR34102012PublicKeyParameters((