diff --git a/securesystemslib/gpg/functions.py b/securesystemslib/gpg/functions.py
index <HASH>..<HASH> 100644
--- a/securesystemslib/gpg/functions.py
+++ b/securesystemslib/gpg/functions.py
@@ -47,7 +47,8 @@ def gpg_sign_object(content, keyid=None, homedir=None):
             Path to the gpg keyring. If not passed the default keyring is used.
 
   <Exceptions>
-    None.
+    ValueError: if the gpg command failed to create a valid signature.
+    OSError: if the gpg command is not present or non-executable.
 
   <Side Effects>
     None.
DOC:gpg:functions: update exception docstrings

The gpg_sign_object did not mention two possible exceptions to raise
when trying to sign an object. Mention those two exceptions and the
reasons as to why they may be raised in the docstrings.