diff --git a/include/micm/util/sparse_matrix.hpp b/include/micm/util/sparse_matrix.hpp
index e4639c1f2..e96956c0e 100644
--- a/include/micm/util/sparse_matrix.hpp
+++ b/include/micm/util/sparse_matrix.hpp
@@ -12,6 +12,7 @@
 #include <stdexcept>
 #include <utility>
 #include <vector>
+#include <iostream>
 
 namespace micm
 {