diff --git a/src/math_functions.cpp b/src/math_functions.cpp
index 32228bcdd5..ba1c6c3db1 100644
--- a/src/math_functions.cpp
+++ b/src/math_functions.cpp
@@ -1,6 +1,6 @@
 #include "openmc/math_functions.h"
 
-#include "Faddeeva.hh"
+#include "openmc/external/Faddeeva.hh"
 
 #include "openmc/constants.h"
 #include "openmc/random_lcg.h"