diff --git a/test_package/nbconvert/env/darwin.txt b/test_package/nbconvert/env/darwin.txt
index a638deb..49d045e 100644
--- a/test_package/nbconvert/env/darwin.txt
+++ b/test_package/nbconvert/env/darwin.txt
@@ -64,7 +64,7 @@ six==1.17.0
     # via python-dateutil
 soupsieve==2.7
     # via beautifulsoup4
-tinycss2==1.4.0
+tinycss2==1.5.1
     # via bleach
 tornado==6.5.1
     # via jupyter-client
diff --git a/test_package/nbconvert/env/linux.txt b/test_package/nbconvert/env/linux.txt
index a638deb..49d045e 100644
--- a/test_package/nbconvert/env/linux.txt
+++ b/test_package/nbconvert/env/linux.txt
@@ -64,7 +64,7 @@ six==1.17.0
     # via python-dateutil
 soupsieve==2.7
     # via beautifulsoup4
-tinycss2==1.4.0
+tinycss2==1.5.1
     # via bleach
 tornado==6.5.1
     # via jupyter-client
diff --git a/test_package/nbconvert/env/win32.txt b/test_package/nbconvert/env/win32.txt
index 14abe46..8062ef4 100644
--- a/test_package/nbconvert/env/win32.txt
+++ b/test_package/nbconvert/env/win32.txt
@@ -66,7 +66,7 @@ six==1.17.0
     # via python-dateutil
 soupsieve==2.7
     # via beautifulsoup4
-tinycss2==1.4.0
+tinycss2==1.5.1
     # via bleach
 tornado==6.5.1
     # via jupyter-client