diff --git a/01.md b/01.md
index 8bf7fc3f..3fd1cdcb 100644
--- a/01.md
+++ b/01.md
@@ -38,7 +38,7 @@ To obtain the `event.id`, we `sha256` the serialized event. The serialization is
   <pubkey, as a (lowercase) hex string>,
   <created_at, as a number>,
   <kind, as a number>,
-  <tags, as an array of arrays of strings>,
+  <tags, as an array of arrays of non-null strings>,
   <content, as a string>
 ]
 ```
diff --git a/02.md b/02.md
index ae3afb80..7309dd50 100644
--- a/02.md
+++ b/02.md
@@ -8,7 +8,7 @@ Contact List and Petnames
 
 A special event with kind `3`, meaning "contact list" is defined as having a list of `p` tags, one for each of the followed/known profiles one is following.
 
-Each tag entry should contain the key for the profile, a relay URL where events from that key can be found (can be set to `null` or a invalid string if not needed), and a local name (or "petname") for that profile (can also be set to `null`), i.e., `["p", <32-bytes hex key>, <main relay URL>, <petname>]`. The `content` can be anything and should be ignored.
+Each tag entry should contain the key for the profile, a relay URL where events from that key can be found (can be set to an empty string if not needed), and a local name (or "petname") for that profile (can also be set to an empty string or not provided), i.e., `["p", <32-bytes hex key>, <main relay URL>, <petname>]`. The `content` can be anything and should be ignored.
 
 For example:
 
@@ -48,7 +48,7 @@ A user has an internal contact list that says
 
 ```json
 [
-  ["p", "21df6d143fb96c2ec9d63726bf9edc71", null, "erin"]
+  ["p", "21df6d143fb96c2ec9d63726bf9edc71", "", "erin"]
 ]
 ```
 
@@ -56,7 +56,7 @@ And receives two contact lists, one from `21df6d143fb96c2ec9d63726bf9edc71` that
 
 ```json
 [
-  ["p", "a8bb3d884d5d90b413d9891fe4c4e46d", null, "david"]
+  ["p", "a8bb3d884d5d90b413d9891fe4c4e46d", "", "david"]
 ]
 ```
 
@@ -64,7 +64,7 @@ and another from `a8bb3d884d5d90b413d9891fe4c4e46d` that says
 
 ```json
 [
-  ["p", "f57f54057d2a7af0efecc8b0b66f5708", null, "frank"]
+  ["p", "f57f54057d2a7af0efecc8b0b66f5708", "", "frank"]
 ]
 ```