diff --git a/src/constraints_mod.F90 b/src/constraints_mod.F90
index 74c9749..3b0f11c 100644
--- a/src/constraints_mod.F90
+++ b/src/constraints_mod.F90
@@ -64,10 +64,9 @@ MODULE CONSTRAINTS_MOD
   !! The file is formated as follows:
   !!
   !! 3 #Number of freezed atoms
-  !! 10  #We are freezing all the coordinates of atom 10
-  !! 20  #We are freezing all the coordinates of atom 10
-  !! 40  #We are freezing all the coordinates of atom 10
-  !! \todo Generalize this to have constrains to different coordinates.
+  !! 10 1 0 0 #We are freezing the x coordinate of atom 10
+  !! 20 1 1 1  #We are freezing all the coordinates of atom 10
+  !! 40 0 0 1  #We are freezing the z coordinate of atom 10
   !!
   !! \param FTOT Total forces. FTOT(1,3) gives the force on x direction for atom 3.
   !! \param VEL Velocities. VEL(1,3) gives the velocity on x direction for atom 3.
@@ -75,7 +74,7 @@ MODULE CONSTRAINTS_MOD
   SUBROUTINE FREEZE_ATOMS(FTOT,VEL)
 
     INTEGER, SAVE :: NFREEZE
-    INTEGER, SAVE, ALLOCATABLE :: FREEZEID(:)
+    INTEGER, SAVE, ALLOCATABLE :: FREEZEID(:), FREEZEIDX(:), FREEZEIDY(:), FREEZEIDZ(:)
     INTEGER :: I
     REAL(DP), OPTIONAL, INTENT(INOUT) :: VEL(:,:)
     REAL(DP), INTENT(INOUT) :: FTOT(:,:)
@@ -84,20 +83,32 @@ SUBROUTINE FREEZE_ATOMS(FTOT,VEL)
        OPEN(444,FILE="freeze.in")
        READ(444,*)NFREEZE
        ALLOCATE(FREEZEID(NFREEZE))
+       ALLOCATE(FREEZEIDX(NFREEZE))
+       ALLOCATE(FREEZEIDY(NFREEZE))
+       ALLOCATE(FREEZEIDZ(NFREEZE))
        DO I = 1,NFREEZE
-          READ(444,*)FREEZEID(I)
+          READ(444,*)FREEZEID(I), FREEZEIDX(I), FREEZEIDY(I), FREEZEIDZ(I)
+          FREEZEIDX(I) = 1 - FREEZEIDX(I)
+          FREEZEIDY(I) = 1 - FREEZEIDY(I)
+          FREEZEIDZ(I) = 1 - FREEZEIDZ(I)
        ENDDO
        CLOSE(444)
     ENDIF
 
     IF(PRESENT(VEL))THEN
        DO I = 1,NFREEZE
-          VEL(:,FREEZEID(I)) = 0.0d0
-          FTOT(:,FREEZEID(I)) = 0.0d0
+          VEL(1,FREEZEID(I)) = REAL(FREEZEIDX(I),DP)*VEL(1,FREEZEID(I))
+          FTOT(1,FREEZEID(I)) = REAL(FREEZEIDX(I),DP)*FTOT(1,FREEZEID(I))
+          VEL(2,FREEZEID(I)) = REAL(FREEZEIDY(I),DP)*VEL(2,FREEZEID(I))
+          FTOT(2,FREEZEID(I)) = REAL(FREEZEIDY(I),DP)*FTOT(2,FREEZEID(I))
+          VEL(3,FREEZEID(I)) = REAL(FREEZEIDZ(I),DP)*VEL(3,FREEZEIDZ(I))
+          FTOT(3,FREEZEID(I)) = REAL(FREEZEIDZ(I),DP)*FTOT(3,FREEZEID(I))
        ENDDO
     ELSE
        DO I = 1,NFREEZE
-          FTOT(:,FREEZEID(I)) = 0.0d0
+          FTOT(1,FREEZEID(I)) = REAL(FREEZEIDX(I),DP)*FTOT(1,FREEZEID(I))
+          FTOT(2,FREEZEID(I)) = REAL(FREEZEIDY(I),DP)*FTOT(2,FREEZEID(I))
+          FTOT(3,FREEZEID(I)) = REAL(FREEZEIDZ(I),DP)*FTOT(3,FREEZEID(I))
        ENDDO
     ENDIF
 
diff --git a/tests/freeze.in b/tests/freeze.in
index 9873ee0..51b60bb 100644
--- a/tests/freeze.in
+++ b/tests/freeze.in
@@ -1,4 +1,4 @@
 3
-1
-2
-3
+1 1 1 1
+2 1 1 1
+3 1 1 1