diff --git a/utils/sample-combine.cpp b/utils/sample-combine.cpp
index 453434c..4323034 100644
--- a/utils/sample-combine.cpp
+++ b/utils/sample-combine.cpp
@@ -25,14 +25,21 @@ using namespace std;
 using namespace Latan;
 
 template <typename T>
-static void loadAndCheck(vector<T> &sample, const vector<string> &fileName)
+static void loadAndCheck(vector<T> &sample __dumb,
+                         const vector<string> &fileName __dumb)
 {
-    const unsigned int n = sample.size();
+    abort();
+}
+
+template <>
+void loadAndCheck(vector<DSample> &sample, const vector<string> &fileName)
+{
+    const unsigned int n = static_cast<unsigned int>(sample.size());
     Index              nSample = 0;
     
     for (unsigned int i = 0; i < n; ++i)
     {
-        sample[i] = Io::load<T>(fileName[i]);
+        sample[i] = Io::load<DSample>(fileName[i]);
         if (i == 0)
         {
             nSample = sample[i].size();
@@ -46,6 +53,65 @@ static void loadAndCheck(vector<T> &sample, const vector<string> &fileName)
     }
 }
 
+template <>
+void loadAndCheck(vector<DMatSample> &sample, const vector<string> &fileName)
+{
+    const unsigned int n = static_cast<unsigned int>(sample.size());
+    Index              nSample = 0;
+    set<unsigned int>  failed;
+    bool               gotSize = false;
+    Index              nRow = 0, nCol = 0;
+    
+    for (unsigned int i = 0; i < n; ++i)
+    {
+        try
+        {
+            sample[i] = Io::load<DMatSample>(fileName[i]);
+            if (!gotSize)
+            {
+                nRow    = sample[i][central].rows();
+                nCol    = sample[i][central].cols();
+                gotSize = true;
+            }
+        }
+        catch (Exceptions::Definition)
+        {
+            failed.insert(i);
+        }
+        if (i == 0)
+        {
+            nSample = sample[i].size();
+        }
+    }
+    for (unsigned int i: failed)
+    {
+        DSample buf;
+        
+        buf = Io::load<DSample>(fileName[i]);
+        sample[i].resize(nSample);
+        FOR_STAT_ARRAY(sample[i], s)
+        {
+            sample[i][s] = DMat::Constant(nRow, nCol, buf[s]);
+        }
+    }
+    for (unsigned int i = 0; i < n; ++i)
+    {
+        if (sample[i].size() != nSample)
+        {
+            cerr << "error: number of sample mismatch (between '";
+            cerr << fileName[0] << "' and '" << fileName[i] << "')" << endl;
+            abort();
+        }
+        if ((sample[i][central].rows() != nRow) and
+            (sample[i][central].cols() != nCol))
+        {
+            cerr << "error: matrix size mismatch (between '";
+            cerr << fileName[0] << "' and '" << fileName[i] << "')" << endl;
+            abort();
+        }
+    }
+}
+
 template <typename T>
 static void combine(const string &outFileName __dumb,
                     const vector<T> &sample __dumb, const string &code __dumb)
@@ -57,7 +123,7 @@ template <>
 void combine(const string &outFileName, const vector<DSample> &sample,
              const string &code)
 {
-    const unsigned int n = sample.size();
+    const unsigned int n = static_cast<unsigned int>(sample.size());
     DoubleFunction     f = compile(code, n);
     DSample            result(sample[0]);
     DVec               buf(n);
@@ -87,7 +153,7 @@ template <>
 void combine(const string &outFileName, const vector<DMatSample> &sample,
              const string &code)
 {
-    const unsigned int n = sample.size();
+    const unsigned int n = static_cast<unsigned int>(sample.size());
     DoubleFunction     f = compile(code, n);
     DVec               buf(n);
     DMatSample         result(sample[0]);