diff --git a/programming/lecture/logical_operations.py b/programming/lecture/logical_operations.py
index 9841fc3..2f54906 100644
--- a/programming/lecture/logical_operations.py
+++ b/programming/lecture/logical_operations.py
@@ -64,6 +64,6 @@ ax4.text(-5.5, 1.025*ax4.get_ylim()[1], "D", fontsize=12)
 
 fig.set_size_inches(3.5, 3.5)
 fig.subplots_adjust(left=0.1, right=0.975, top=0.95, bottom=0.12, hspace=0.3)
-fig.savefig("logical_operations.png")
+fig.savefig("logical_operations.pdf")
 plt.close()