diff --git a/demo/api/requirements.txt b/demo/api/requirements.txt
index 5f26b9e..017c358 100644
--- a/demo/api/requirements.txt
+++ b/demo/api/requirements.txt
@@ -17,7 +17,7 @@ mock==2.0.0
 nltk==3.4
 numpy==1.16.2
 pbr==5.1.3
-protobuf==3.7.0
+protobuf==3.15.0
 PyYAML==5.1
 scipy==1.2.1
 singledispatch==3.4.0.3