diff --git a/lib/syntax.default b/lib/syntax.default
index 0a4a193d78..f713cfae8a 100644
--- a/lib/syntax.default
+++ b/lib/syntax.default
@@ -697,6 +697,7 @@ $$
 \begin{environments}
 bibunit[]{translate}
 psmatrix[]{}
+theorem[]{translate} % from amsthm.sty and probably others
 thebibliography{}
 \end{environments}
 
diff --git a/status.20x b/status.20x
index fec6b88e07..0a5ba22740 100644
--- a/status.20x
+++ b/status.20x
@@ -158,6 +158,8 @@ What's new
 
 - Fix (La)TeX import of shaded boxes (bug 7843).
 
+- Fix LaTeX import of theorem environment with optional argument (bug 6834).
+
 - Store the autosave files of unnamed buffers in the correct directory
   and make sure they are not left behind after saving (bug 7793).