diff --git a/requirements.txt b/requirements.txt
index 28d449c..5bc29eb 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,7 +4,7 @@
 Cython == 0.29.21
 
 # pysbpl/pysbpl/map_util.py: 4
-PyYAML == 5.3.1
+PyYAML == 5.4
 
 # pysbpl/pysbpl/gen_mprim.py: 11
 # pysbpl/pysbpl/plot.py: 3,4