diff --git a/matlab/+pac/+estimate/nls.m b/matlab/+pac/+estimate/nls.m
index 779f10ab3..726b9953d 100644
--- a/matlab/+pac/+estimate/nls.m
+++ b/matlab/+pac/+estimate/nls.m
@@ -193,8 +193,8 @@ else
       case 'GaussNewton'
         % Nothing to do here.
       case 'lsqnonlin'
-        bounds = ones(length(params0),1)*[-10,10];
-        bounds(strcmp(fieldnames(params), M_.param_names(M_.pac.pacman.ec.params)),1)  = .0;
+        bounds = ones(length(params0),1)*[-Inf,Inf];
+        bounds(strcmp(fieldnames(params), M_.param_names(M_.pac.(pacmodl).ec.params)),1)  = .0;
       case 'fmincon'
         if isoctave
             error('Optimization algorithm ''fmincon'' is not available under Octave')
@@ -202,8 +202,8 @@ else
             error('Optimization algorithm ''fmincon'' requires the Optimization Toolbox')
         end
         minalgo = 1;
-        bounds = ones(length(params0),1)*[-10,10];
-        bounds(strcmp(fieldnames(params), M_.param_names(M_.pac.pacman.ec.params)),1)  = .0;
+        bounds = ones(length(params0),1)*[-Inf,Inf];
+        bounds(strcmp(fieldnames(params), M_.param_names(M_.pac.(pacmodl).ec.params)),1)  = .0;
       case 'fminunc'
         if isoctave && ~user_has_octave_forge_package('optim')
             error('Optimization algorithm ''fminunc'' requires the optim package')
@@ -224,8 +224,8 @@ else
         minalgo = 8;
       case 'annealing'
         minalgo = 2;
-        bounds = ones(length(params0),1)*[-10,10];
-        bounds(strcmp(fieldnames(params), M_.param_names(M_.pac.pacman.ec.params)),1)  = .0;
+        bounds = ones(length(params0),1)*[-Inf,Inf];
+        bounds(strcmp(fieldnames(params), M_.param_names(M_.pac.(pacmodl).ec.params)),1)  = .0;
         parameter_names = fieldnames(params);
       case 'particleswarm'
         if isoctave
@@ -234,8 +234,8 @@ else
             error('Optimization ''particleswarm'' requires the Global Optimization Toolbox')
         end
         minalgo = 12;
-        bounds = ones(length(params0),1)*[-10,10];
-        bounds(strcmp(fieldnames(params), M_.param_names(M_.pac.pacman.ec.params)),1)  = .0;
+        bounds = ones(length(params0),1)*[-Inf,Inf];
+        bounds(strcmp(fieldnames(params), M_.param_names(M_.pac.(pacmodl).ec.params)),1)  = .0;
         parameter_names = fieldnames(params);
       otherwise
         msg = sprintf('%s is not an implemented optimization routine.\n', optimizer);