diff --git a/quartodoc/autosummary.py b/quartodoc/autosummary.py
index b3169bd..91d5a91 100644
--- a/quartodoc/autosummary.py
+++ b/quartodoc/autosummary.py
@@ -592,8 +592,9 @@ def build(self, filter: str = "*"):
 
         if self.source_dir:
             import sys
-
-            sys.path.append(self.source_dir)
+            
+            if self.source_dir != sys.path[0]:
+                sys.path.insert(0, self.source_dir)
 
         # shaping and collection ----