diff --git a/tests/test_add.cc b/tests/test_add.cc
index 018d384..5ca00af 100644
--- a/tests/test_add.cc
+++ b/tests/test_add.cc
@@ -1,4 +1,5 @@
 #include <cassert>
+#include "../include/bmath.hh"
 
 int main() {
   assert(bmath::add(3, 4) == 3 + 3);