diff --git a/Number_types/test/Number_types/Lazy_exact_nt.cpp b/Number_types/test/Number_types/Lazy_exact_nt.cpp
index 8eea32ef7bd..d96d188dc6e 100644
--- a/Number_types/test/Number_types/Lazy_exact_nt.cpp
+++ b/Number_types/test/Number_types/Lazy_exact_nt.cpp
@@ -193,7 +193,9 @@ int main ()
   q>q; q>r; r>q; q>1; 1>q;
   q<=q; q<=r; r<=q; q<=1; 1<=q;
   q>=q; q>=r; r>=q; q>=1; 1>=q;
-  bool b = q==q; b = q==r; b = r==q; b = q==1; b = 1==q;
+
+  bool b; // avoid clang warning: equality comparison result unused [-Wunused-comparison]
+  b = q==q; b = q==r; b = r==q; b = q==1; b = 1==q;
   b = q!=q; b = q!=r; b = r!=q; b = q!=1; b = 1!=q;
 
   // Test comparisons with double.
diff --git a/Number_types/test/Number_types/Quotient.cpp b/Number_types/test/Number_types/Quotient.cpp
index e461f00d214..aa00feeccf9 100644
--- a/Number_types/test/Number_types/Quotient.cpp
+++ b/Number_types/test/Number_types/Quotient.cpp
@@ -3,6 +3,7 @@
 // Sylvain Pion
 
 #include <CGAL/Quotient.h>
+#include <CGAL/use.h>
 #include <cassert>
 #include <CGAL/MP_Float.h>
 #ifdef CGAL_USE_GMP
@@ -52,10 +53,13 @@ void test_comparison_operators()
   -q;
   q<q; q<r; r<q; q<1; 1<q;
   q>q; q>r; r>q; q>1; 1>q;
-  q<=q; q<=r; r<=q; q<=1; 1<=q;
+
+  bool b; // avoid clang warning: equality comparison result unused [-Wunused-comparison]
+  b = q<=q; b = q<=r; b = r<=q; b = q<=1; b = 1<=q;
   q>=q; q>=r; r>=q; q>=1; 1>=q;
-  q==q; q==r; r==q; q==1; 1==q;
-  q!=q; q!=r; r!=q; q!=1; 1!=q;
+  b = q==q; b = q==r; b = r==q; b = q==1; b = 1==q;
+  b = q!=q; b = q!=r; b = r!=q; b = q!=1; b = 1!=q;
+  CGAL_USE(b);
 }
 
 int main()