diff --git a/index.md b/index.md
index b856b1e87c48009247987357dca1e8757fec6772..185807ac5cb3e2081be6e87a5fe8b475855f9fc6 100644
--- a/index.md
+++ b/index.md
@@ -6,13 +6,13 @@ nav_order: 1
 
 # Computer Vision
 
-## [Camera Sensors]({{ '/topics/1_cameras' | relative_url }})
+## [Camera Sensors]({{ '/topics/01_cameras' | relative_url }})
 
 Sensor basics
 
-## [Passive Scanning]({{ '/topics/2_passive' | relative_url }})
+## [Passive Scanning]({{ '/topics/02_passive' | relative_url }})
 
 
-## [Active Scanning]({{ '/topics/3_active' | relative_url }})
+## [Active Scanning]({{ '/topics/03_active' | relative_url }})
 
-## [Mechanical Digitizing]({{ '/topics/4_mechanical' | relative_url }})
+## [Mechanical Digitizing]({{ '/topics/04_mechanical' | relative_url }})