diff --git a/Number_types/include/CGAL/leda_bigfloat.h b/Number_types/include/CGAL/leda_bigfloat.h
index 8c0041db670..a770729cd0b 100644
--- a/Number_types/include/CGAL/leda_bigfloat.h
+++ b/Number_types/include/CGAL/leda_bigfloat.h
@@ -21,10 +21,11 @@
 //
 // Author(s)     : Stefan Schirra, Michael Hemmer
 
-
 #ifndef CGAL_LEDA_BIGFLOAT_H
 #define CGAL_LEDA_BIGFLOAT_H
 
+#ifdef CGAL_USE_LEDA
+
 #include <CGAL/number_type_basic.h>
 
 #include <utility>
@@ -158,4 +159,6 @@ namespace leda {
 #include <CGAL/leda_bigfloat.h>
 #include <CGAL/leda_real.h>
 
+#endif // CGAL_USE_LEDA
+
 #endif // CGAL_LEDA_BIGFLOAT_H
diff --git a/Number_types/include/CGAL/leda_integer.h b/Number_types/include/CGAL/leda_integer.h
index 6b60035d671..6b878db6d5c 100644
--- a/Number_types/include/CGAL/leda_integer.h
+++ b/Number_types/include/CGAL/leda_integer.h
@@ -24,6 +24,8 @@
 #ifndef CGAL_LEDA_INTEGER_H
 #define CGAL_LEDA_INTEGER_H
 
+#ifdef CGAL_USE_LEDA
+
 #include <CGAL/number_type_basic.h>
 
 #include <utility>
@@ -258,4 +260,6 @@ namespace leda {
 #include <CGAL/leda_bigfloat.h>
 #include <CGAL/leda_real.h>
 
+#endif // CGAL_USE_LEDA
+
 #endif // CGAL_LEDA_INTEGER_H
diff --git a/Number_types/include/CGAL/leda_rational.h b/Number_types/include/CGAL/leda_rational.h
index 1c2def22bb8..360dd729581 100644
--- a/Number_types/include/CGAL/leda_rational.h
+++ b/Number_types/include/CGAL/leda_rational.h
@@ -21,10 +21,11 @@
 //
 // Author(s)     : Andreas Fabri, Michael Hemmer
 
-
 #ifndef CGAL_LEDA_RATIONAL_H
 #define CGAL_LEDA_RATIONAL_H
 
+#ifdef CGAL_USE_LEDA
+
 #include <CGAL/number_type_basic.h>
 #include <CGAL/leda_coercion_traits.h>
 #include <CGAL/Interval_nt.h>
@@ -287,4 +288,6 @@ inline rational operator+( const rational& i) { return i; }
 #include <CGAL/leda_bigfloat.h>
 #include <CGAL/leda_real.h>
 
+#endif // CGAL_USE_LEDA
+
 #endif  // CGAL_LEDA_RATIONAL_H
diff --git a/Number_types/include/CGAL/leda_real.h b/Number_types/include/CGAL/leda_real.h
index bc4b36b9a40..d95a377c707 100644
--- a/Number_types/include/CGAL/leda_real.h
+++ b/Number_types/include/CGAL/leda_real.h
@@ -24,6 +24,8 @@
 #ifndef CGAL_LEDA_REAL_H
 #define CGAL_LEDA_REAL_H
 
+#ifdef CGAL_USE_LEDA
+
 #include <CGAL/number_type_basic.h>
 #include <CGAL/leda_coercion_traits.h>
 
@@ -255,4 +257,6 @@ namespace leda {
 #include <CGAL/leda_bigfloat.h>
 #include <CGAL/leda_real.h>
 
+#endif // CGAL_USE_LEDA
+
 #endif // CGAL_LEDA_REAL_H