[R] matrix subset

[vincent@7d4.com]

Dear R-helpers,

I apologize for this certainly simple question.
I have the following R lines :

 > m  = matrix(1:12 , 3 , 4);
 > m
      [,1] [,2] [,3] [,4]
[1,]    1    4    7   10
[2,]    2    5    8   11
[3,]    3    6    9   12

 > m1 = subset(m , m[,2]>=5);
 > m1
[1]  2  3  5  6  8  9 11 12

but in fact I would appreciate m1 to be also a matrix,
and thus would like to get :

 > m1
      [,1] [,2] [,3] [,4]
[2,]    2    5    8   11
[3,]    3    6    9   12

... but I don't find how to do ?
(probably it is very simple ! double shame.).
Thanks for any hint or pointer.
Vincent