Update formats.py

mwouts · Mar 29, 2020 · 8a8fb3d · 8a8fb3d
1 parent 39a262f
commit 8a8fb3d
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/jupytext/formats.py b/jupytext/formats.py
@@ -232,7 +232,7 @@ def read_format_from_metadata(text, ext):
 
 def guess_format(text, ext):
     """Guess the format and format options of the file, given its extension and content"""
-    if matches_mystnb(text, ext):
+    if is_myst_available() and matches_mystnb(text, ext):
         return MYST_FORMAT_NAME, {}
     lines = text.splitlines()