diff --git a/sparse_to_csr.m b/sparse_to_csr.m
index 588380d..9538eba 100644
--- a/sparse_to_csr.m
+++ b/sparse_to_csr.m
@@ -21,15 +21,16 @@
 % 2008-04-07: Initial version
 % 2008-04-24: Added triple array input
 % 2009-05-01: Added ncol output
+% 2009-05-15: Fixed triplet input
 
-error(nargchk(1, 4, nargin, 'struct'))
+error(nargchk(1, 5, nargin, 'struct'))
 retc = nargout>1; reta = nargout>2;
 
 if nargin>1
-    n = varargin{3};
     if nargin>4, ncol = varargin{4}; end
     nzi = A; nzj = varargin{1};
     if reta && length(varargin) > 2, nzv = varargin{2}; end    
+    if nargin<4, n=max(nzi); else n=varargin{3}; end
     nz = length(A);
     if length(nzi) ~= length(nzj), error('gaimc:invalidInput',...
             'length of nzi (%i) not equal to length of nzj (%i)', nz, ...
@@ -40,9 +41,10 @@
     end
     if ~isscalar(n), error('gaimc:invalidInput',...
             ['the 4th input to sparse_to_csr with triple input was not ' ...
-             'a scalar']); end
+             'a scalar']); 
+    end
     if nargin < 5, ncol = max(nzj); 
-    elif ~isscalar(ncol), error('gaimc:invalidInput',...
+    elseif ~isscalar(ncol), error('gaimc:invalidInput',...
             ['the 5th input to sparse_to_csr with triple input was not ' ...
              'a scalar']); 
     end
diff --git a/test/test_sparse_to_csr.m b/test/test_sparse_to_csr.m
index fa0b470..ff4f65c 100644
--- a/test/test_sparse_to_csr.m
+++ b/test/test_sparse_to_csr.m
@@ -1,4 +1,8 @@
 function test_sparse_to_csr
+%% Previous failure
+[ai,aj,av]=find(ones(5));
+sparse_to_csr(ai,aj,av);
+
 %% 100 random trials
 for t=1:100
     A = sprand(100,80,0.01);