diff --git a/interfaces/matlab/toolbox/IdealGasMix.m b/interfaces/matlab/toolbox/IdealGasMix.m
index 17810a64b..b7c12a7b3 100755
--- a/interfaces/matlab/toolbox/IdealGasMix.m
+++ b/interfaces/matlab/toolbox/IdealGasMix.m
@@ -32,8 +32,8 @@ function s = IdealGasMix(a,b,c)
 %   See also: ck2ctml, Solution
 %
 dotloc = findstr(a,'.');
-if dotloc > 1
-   ext = a(dotloc:end);
+if dotloc(end) > 1
+   ext = a(dotloc(end):end);
    if ~strcmp(ext,'.inp')
      if nargin == 1
        s = Solution(a);
diff --git a/interfaces/matlab/toolbox/ck2cti.m b/interfaces/matlab/toolbox/ck2cti.m
index 7ea5ee168..fa4315ebe 100644
--- a/interfaces/matlab/toolbox/ck2cti.m
+++ b/interfaces/matlab/toolbox/ck2cti.m
@@ -33,8 +33,8 @@ elseif nargin == 2
 end
     
 dotloc = findstr(infile,'.');
-if dotloc > 1
-   idtag = infile(1:dotloc-1);
+if dotloc(end) > 1
+   idtag = infile(1:dotloc(end)-1);
    outfile = [idtag '.cti'];
 else
    idtag = infile;
diff --git a/interfaces/matlab/toolbox/ck2ctml.m b/interfaces/matlab/toolbox/ck2ctml.m
index c91abefb9..3aef53dc9 100644
--- a/interfaces/matlab/toolbox/ck2ctml.m
+++ b/interfaces/matlab/toolbox/ck2ctml.m
@@ -30,8 +30,8 @@ elseif nargin == 2
 end
     
 dotloc = findstr(infile,'.');
-if dotloc > 1
-   idtag = infile(1:dotloc-1);
+if dotloc(end) > 1
+   idtag = infile(1:dotloc(end)-1);
    outfile = [idtag '.xml'];
 else
    idtag = infile;