diff --git a/pinecone/utils/user_agent.py b/pinecone/utils/user_agent.py
index c0b413da..aeda857b 100644
--- a/pinecone/utils/user_agent.py
+++ b/pinecone/utils/user_agent.py
@@ -7,7 +7,7 @@
 def _build_source_tag_field(source_tag):
     # normalize source tag
     # 1. Lowercase
-    # 2. Limit charset to [a-z0-9_ ]
+    # 2. Limit charset to [a-z0-9_ :]
     # 3. Trim left/right whitespace
     # 4. Condense multiple spaces to one, and replace with underscore
     tag = source_tag.lower()