diff --git a/docs/new_packages.md b/docs/new_packages.md
index 8842a353a..438e878eb 100644
--- a/docs/new_packages.md
+++ b/docs/new_packages.md
@@ -68,10 +68,12 @@ The tarball may be in any of the formats supported by Python's
 #### `source/md5`
 
 The MD5 checksum of the tarball. It is recommended to use SHA256 instead of MD5.
+At most one checksum entry sould be provided per package.
 
 #### `source/sha256`
 
 The SHA256 checksum of the tarball. It is recommended to use SHA256 instead of MD5.
+At most one checksum entry sould be provided per package.
 
 #### `source/patches`