diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
index e480770b..cb3bd962 100644
--- a/include/CMakeLists.txt
+++ b/include/CMakeLists.txt
@@ -1,3 +1,3 @@
-project(headers)
+project(headers C)
 
 add_subdirectory(libssh)
diff --git a/include/libssh/CMakeLists.txt b/include/libssh/CMakeLists.txt
index 05605106..bfbebdd8 100644
--- a/include/libssh/CMakeLists.txt
+++ b/include/libssh/CMakeLists.txt
@@ -1,4 +1,4 @@
-project(libssh-headers)
+project(libssh-headers C)
 
 set(libssh_HDRS
   libssh.h
diff --git a/libssh/CMakeLists.txt b/libssh/CMakeLists.txt
index 62ee95ef..91ee3ccb 100644
--- a/libssh/CMakeLists.txt
+++ b/libssh/CMakeLists.txt
@@ -1,4 +1,4 @@
-project(libssh-library)
+project(libssh-library C)
 
 set(LIBSSH_PUBLIC_INCLUDE_DIRS
   ${CMAKE_SOURCE_DIR}/include