diff --git a/1-Introduction/4-techniques-of-ML/README.md b/1-Introduction/4-techniques-of-ML/README.md
index 1b87fd7c..3b46b036 100644
--- a/1-Introduction/4-techniques-of-ML/README.md
+++ b/1-Introduction/4-techniques-of-ML/README.md
@@ -25,7 +25,7 @@ Computers are particularly skilled at discovering hidden patterns in data. This
 
 When many other variables are brought into the equation, however, a ML model might prove more efficient to predict future mortality rates based on past health history. A more cheerful example might be making weather predictions for the month of April in a given location based on data that includes latitude, longitude, climate change, proximity to the ocean, patterns of the jet stream, and more.
 
-✅ This [slide deck](https://www2.cisl.ucar.edu/sites/default/files/0900%20June%2024%20Haupt_0.pdf) on weather models offers a historical perspective for using ML in weather analysis.  
+✅ This [slide deck](https://www2.cisl.ucar.edu/sites/default/files/2021-10/0900%20June%2024%20Haupt_0.pdf) on weather models offers a historical perspective for using ML in weather analysis.  
 
 ## Pre-building tasks