diff --git a/src/util/rational.h b/src/util/rational.h
index 1bafd739c..d80db5f06 100644
--- a/src/util/rational.h
+++ b/src/util/rational.h
@@ -132,7 +132,7 @@ public:
 
     rational const & get_infinitesimal() const { return m_zero; }
 
-    rational & operator=(rational&&) noexcept = default;
+    rational & operator=(rational&&) = default;
 
     rational & operator=(rational const & r) {
         m().set(m_val, r.m_val);