diff --git a/sonar-project.properties b/sonar-project.properties
index 91b8fda47..dc11acaf7 100644
--- a/sonar-project.properties
+++ b/sonar-project.properties
@@ -9,6 +9,7 @@ sonar.host.url=https://sonarcloud.io
 # prior to SonarQube 6.1.
 sonar.projectName=libtorrent
 sonar.projectVersion=1.2
+sonar.language=c++
 
 # to allow shallow clones
 sonar.scm.disabled=true