diff --git a/src/source.cpp b/src/source.cpp
index cd8b5e5743..5e26fa0a8d 100644
--- a/src/source.cpp
+++ b/src/source.cpp
@@ -31,6 +31,10 @@
 #include "openmc/state_point.h"
 #include "openmc/xml_interface.h"
 
+#ifdef HAS_MCPL
+#include <mcpl.h>
+#endif
+
 namespace openmc {
 
 //==============================================================================