diff --git a/.travis.yml b/.travis.yml
index 11dd4c2..7f103f6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -60,7 +60,7 @@ script:
   - $CXX --version
 
   # put json.hpp to nlohmann
-  - mkdir -p nlohmann && wget https://github.com/nlohmann/json/releases/download/v3.6.0/json.hpp -O nlohmann/json.hpp
+  - mkdir -p nlohmann && wget https://github.com/nlohmann/json/releases/download/v3.8.0/json.hpp -O nlohmann/json.hpp
 
   # compile and execute unit tests
   - mkdir -p build && cd build