diff --git a/docs/x509.rst b/docs/x509.rst
index 7eb47a3..751e077 100644
--- a/docs/x509.rst
+++ b/docs/x509.rst
@@ -488,7 +488,7 @@
 .. data:: OID_BASIC_CONSTRAINTS
 
     Corresponds to the dotted string ``"2.5.29.19"``. The identifier for the
-    basic constraints extension.
+    :class:`BasicConstraints` extension type.
 
 
 Exceptions
diff --git a/src/cryptography/x509.py b/src/cryptography/x509.py
index d64d61f..4ba6956 100644
--- a/src/cryptography/x509.py
+++ b/src/cryptography/x509.py
@@ -175,7 +175,7 @@
         if not isinstance(ca, bool):
             raise TypeError("ca must be a boolean value")
 
-        if path_length is not None and ca is False:
+        if path_length is not None and not ca:
             raise ValueError("path_length must be None when ca is False")
 
         if path_length is not None and (not isinstance(path_length, int)