diff --git a/src/include/real.cpp b/src/include/real.cpp
index 3adc26289..a61e0dc2d 100755
--- a/src/include/real.cpp
+++ b/src/include/real.cpp
@@ -2,6 +2,7 @@
 #include <real.h>
 #include <strings.h>
 
+const real MENOUNO(-1.0);
 const real ZERO(0.0);
 const real PUNTO_UNO(UNO/DIECI);
 const real PUNTO_DUE(DUE/DIECI);
diff --git a/src/include/real.h b/src/include/real.h
index 7de8b504c..abd7471a6 100755
--- a/src/include/real.h
+++ b/src/include/real.h
@@ -11,6 +11,7 @@
 
 class real;
 
+extern const real MENOUNO;
 extern const real ZERO;
 extern const real PUNTO_UNO;
 extern const real PUNTO_DUE;