diff --git a/duniterpy/key/signing_key.py b/duniterpy/key/signing_key.py
index d3be68ae4ce2de95bf80c9913e47df6bf5cd4d6b..5abc00df859f6ca72d9bdae02307a77c90a14efa 100644
--- a/duniterpy/key/signing_key.py
+++ b/duniterpy/key/signing_key.py
@@ -146,7 +146,7 @@ class SigningKey(libnacl.sign.Signer):
 
         # line patterns
         regex_pubkey = re.compile("pub: ([1-9A-HJ-NP-Za-km-z]{43,44})", re.MULTILINE)
-        regex_signkey = re.compile("sec: ([1-9A-HJ-NP-Za-km-z]{88,90})", re.MULTILINE)
+        regex_signkey = re.compile("sec: ([1-9A-HJ-NP-Za-km-z]{87,90})", re.MULTILINE)
 
         # check public key field
         match = re.search(regex_pubkey, pubsec_content)