diff --git a/docs/KNOWN_BUGS b/docs/KNOWN_BUGS
index 43e008dee..5363575ef 100644
--- a/docs/KNOWN_BUGS
+++ b/docs/KNOWN_BUGS
@@ -44,6 +44,7 @@ problems may have been fixed or changed somewhat since this was written!
  4.5 Improve --data-urlencode space encoding
 
  5. Build and portability issues
+ 5.1 tests not compatible with python3
  5.2 curl-config --libs contains private details
  5.5 can't handle Unicode arguments in Windows
  5.6 cmake support gaps
@@ -354,6 +355,12 @@ problems may have been fixed or changed somewhat since this was written!
 
 5. Build and portability issues
 
+5.1 tests not compatible with python3
+
+ The smb test server still needs python2.
+
+ See https://github.com/curl/curl/issues/3289
+
 5.2 curl-config --libs contains private details
 
  "curl-config --libs" will include details set in LDFLAGS when configure is