diff --git a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -35,6 +35,8 @@
 CHECK_TYPE_SIZE("long long" LONG_LONG)
 SET(LEMON_HAVE_LONG_LONG ${HAVE_LONG_LONG})
 
+INCLUDE(FindPythonInterp)
+
 ENABLE_TESTING()
 
 ADD_SUBDIRECTORY(lemon)