diff --git a/CMakeLists.txt b/CMakeLists.txt
index e5680d7..3867919 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -109,3 +109,7 @@ target_link_libraries(mcc
     ${LLVM_LIBRARIES}
 )
 
+## 6. Build the runtime library too
+
+add_library(mcrt STATIC Runtime.cpp)
+
diff --git a/Runtime.c b/Runtime.cpp
similarity index 96%
rename from Runtime.c
rename to Runtime.cpp
index 48155d7..1c5c944 100644
--- a/Runtime.c
+++ b/Runtime.cpp
@@ -17,11 +17,11 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "Runtime.h"
+#include "Runtime.hpp"
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <assert.h>
+#include <cstdio>
+#include <cstdlib>
+#include <cassert>
 
 
 void __Monicelli_main();
diff --git a/Runtime.h b/Runtime.hpp
similarity index 100%
rename from Runtime.h
rename to Runtime.hpp