diff --git a/requirements.in b/requirements.in
index 075abf2..8d30a43 100644
--- a/requirements.in
+++ b/requirements.in
@@ -1 +1 @@
-protobuf==3.15.0
+protobuf==3.18.3
diff --git a/requirements.txt b/requirements.txt
index 154da77..0e4f0ce 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,7 +4,5 @@
 #
 #    pip-compile --output-file requirements.txt requirements.in
 #
-protobuf==3.15.0
+protobuf==3.18.3
     # via -r requirements.in
-six==1.10.0
-    # via protobuf