diff --git a/Modular_arithmetic/src/CGAL/Residue_type.cpp b/Modular_arithmetic/src/CGAL/Residue_type.cpp
index e8c18870375..e41a63a907b 100644
--- a/Modular_arithmetic/src/CGAL/Residue_type.cpp
+++ b/Modular_arithmetic/src/CGAL/Residue_type.cpp
@@ -19,6 +19,7 @@
 
 #ifndef CGAL_HEADER_ONLY
 
+#include <CGAL/Residue.h>
 #include <CGAL/Modular_arithmetic/Residue_type.h>
 
 namespace CGAL{