diff --git a/src/tight_inclusion/ccd.cpp b/src/tight_inclusion/ccd.cpp
index 1369b9d..a431d19 100644
--- a/src/tight_inclusion/ccd.cpp
+++ b/src/tight_inclusion/ccd.cpp
@@ -4,6 +4,7 @@
 #include <tight_inclusion/timer.hpp>
 
 #include <vector>
+#include <cassert>
 
 namespace ticcd {
 
diff --git a/src/tight_inclusion/interval.cpp b/src/tight_inclusion/interval.cpp
index 3b356dd..61d2418 100644
--- a/src/tight_inclusion/interval.cpp
+++ b/src/tight_inclusion/interval.cpp
@@ -1,6 +1,8 @@
 // An interval object.
 #include "interval.hpp"
 
+#include <cassert>
+
 namespace ticcd {
 
     static constexpr uint8_t MAX_DENOM_POWER = 8 * sizeof(uint64_t) - 1;