diff --git a/CMakeLists.txt b/CMakeLists.txt
index 648d07db..a80eae58 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -15,7 +15,7 @@
 #
 
 cmake_minimum_required(VERSION 3.1)
-project(ZNC VERSION 1.8.0)
+project(ZNC VERSION 1.8.0 LANGUAGES CXX)
 set(ZNC_VERSION 1.8.x)
 set(append_git_version true)
 set(alpha_version "") # e.g. "-rc1"
diff --git a/cmake/cxx11check/CMakeLists.txt b/cmake/cxx11check/CMakeLists.txt
index e5936fe6..b83740cd 100644
--- a/cmake/cxx11check/CMakeLists.txt
+++ b/cmake/cxx11check/CMakeLists.txt
@@ -15,7 +15,7 @@
 #
 
 cmake_minimum_required(VERSION 3.0)
-project(cxx11check)
+project(cxx11check LANGUAGES CXX)
 set(CMAKE_VERBOSE_MAKEFILE true)
 
 set(CMAKE_CXX_STANDARD 11)
diff --git a/cmake/perl_check/CMakeLists.txt b/cmake/perl_check/CMakeLists.txt
index 5ecc7057..86fa1219 100644
--- a/cmake/perl_check/CMakeLists.txt
+++ b/cmake/perl_check/CMakeLists.txt
@@ -15,7 +15,7 @@
 #
 
 cmake_minimum_required(VERSION 3.0)
-project(perl_check)
+project(perl_check LANGUAGES CXX)
 set(CMAKE_VERBOSE_MAKEFILE true)
 
 if(APPLE)
diff --git a/test/integration/CMakeLists.txt b/test/integration/CMakeLists.txt
index 033eb5b2..a6eb3e7e 100644
--- a/test/integration/CMakeLists.txt
+++ b/test/integration/CMakeLists.txt
@@ -15,7 +15,7 @@
 #
 
 cmake_minimum_required(VERSION 3.0)
-project(ZNCIntegrationTest)
+project(ZNCIntegrationTest LANGUAGES CXX)
 
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD_REQUIRED true)
diff --git a/znc-buildmod.cmake.in b/znc-buildmod.cmake.in
index 356cf01c..e6a55b19 100755
--- a/znc-buildmod.cmake.in
+++ b/znc-buildmod.cmake.in
@@ -57,7 +57,7 @@ args = parser.parse_args()
 with tempfile.TemporaryDirectory() as cmdir:
     with open(os.path.join(cmdir, 'CMakeLists.txt'), 'w') as cm:
         print('cmake_minimum_required(VERSION 3.1)', file=cm)
-        print('project(ExternalModules)', file=cm)
+        print('project(ExternalModules LANGUAGES CXX)', file=cm)
         print('find_package(ZNC @ZNC_VERSION_MAJOR@.@ZNC_VERSION_MINOR@ HINTS '
             '@CMAKE_INSTALL_FULL_DATADIR@/znc REQUIRED)', file=cm)
         if args.verbose > 0: