diff --git a/README.adoc b/README.adoc
index 08a369c..7f61a86 100644
--- a/README.adoc
+++ b/README.adoc
@@ -87,7 +87,7 @@ If you get the error message that `add-apt-repository` was not found, install
 * link:{uri-termcolor}[Termcolor] (tested: 2.0) (If not found, the bundled
   version is used.)
 * link:{uri-pugixml}[pugixml] (tested: 1.11 / 1.8)
-* link:{uri-json}[nlohmann_json] (tested: 3.9 / 2.0)
+* link:{uri-json}[nlohmann_json] (tested: 3.9 / 2.1)
 * Optional
   ** Tests: link:{uri-catch}[Catch] (tested: 2.13 / 1.10)