diff --git a/src/util/interval/interval.cpp b/src/util/interval/interval.cpp
index 36fcde31e..6fc5000fd 100644
--- a/src/util/interval/interval.cpp
+++ b/src/util/interval/interval.cpp
@@ -6,6 +6,7 @@ Author: Leonardo de Moura
         Soonho Kong
 */
 #pragma once
+#include <cstddef>
 #include <gmp.h>
 #include <mpfr.h>
 #include <utility>
diff --git a/src/util/numerics/double.h b/src/util/numerics/double.h
index 4a908f411..34d4e84e6 100644
--- a/src/util/numerics/double.h
+++ b/src/util/numerics/double.h
@@ -5,6 +5,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Soonho Kong
 */
 #pragma once
+#include <cstddef>
 #include <mpfr.h>
 #include "util/numerics/mpfp.h"
 
diff --git a/src/util/numerics/float.h b/src/util/numerics/float.h
index c9cd5796e..7a11d842e 100644
--- a/src/util/numerics/float.h
+++ b/src/util/numerics/float.h
@@ -5,6 +5,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Soonho Kong
 */
 #pragma once
+#include <cstddef>
 #include <mpfr.h>
 #include "util/numerics/mpfp.h"
 
diff --git a/src/util/numerics/init_module.cpp b/src/util/numerics/init_module.cpp
index c3ae5aa21..4ad081f3e 100644
--- a/src/util/numerics/init_module.cpp
+++ b/src/util/numerics/init_module.cpp
@@ -4,6 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 
 Author: Leonardo de Moura
 */
+#include <cstddef>
 #include <gmp.h>
 #include "util/memory.h"
 #include "util/numerics/mpz.h"
diff --git a/src/util/numerics/mpfp.h b/src/util/numerics/mpfp.h
index 0c0c37218..ab9f9deb1 100644
--- a/src/util/numerics/mpfp.h
+++ b/src/util/numerics/mpfp.h
@@ -6,6 +6,7 @@ Author: Soonho Kong
 */
 #pragma once
 #include <stdint.h>
+#include <cstddef>
 #include <mpfr.h>
 #include "util/numerics/mpz.h"
 #include "util/numerics/mpq.h"
diff --git a/src/util/numerics/mpz.h b/src/util/numerics/mpz.h
index c872e6207..84ccb7915 100644
--- a/src/util/numerics/mpz.h
+++ b/src/util/numerics/mpz.h
@@ -5,6 +5,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
+#include <cstddef>
 #include <gmp.h>
 #include <iostream>
 #include "util/debug.h"