attr: fix typo
diff --git a/include/git2/attr.h b/include/git2/attr.h
index a58d21b..651454a 100644
--- a/include/git2/attr.h
+++ b/include/git2/attr.h
@@ -196,7 +196,7 @@ GIT_EXTERN(int) git_attr_get_many(
* @see git_attr_foreach.
*
* @param name The attribute name.
- * @param value The attribute value. May be NULL is the attribute is explicitly
+ * @param value The attribute value. May be NULL if the attribute is explicitly
* set to UNSPECIFIED using the '!' sign.
* @param payload A user-specified pointer.
* @return 0 to continue looping, non-zero to stop. This value will be returned