diff --git a/efel/cppcore/LibV1.cpp b/efel/cppcore/LibV1.cpp
index 80550678..25c1eee1 100644
--- a/efel/cppcore/LibV1.cpp
+++ b/efel/cppcore/LibV1.cpp
@@ -434,7 +434,6 @@ static int __burst_ISI_indices(double BurstFactor, vector<int>& PeakIndex,
                                vector<double>& ISIValues,
                                vector<int>& BurstIndex) {
   vector<double> ISIpcopy;
-  vector<double>::iterator it1, it2;
   int n, count = -1;
   double dMedian;
 
diff --git a/efel/cppcore/Utils.h b/efel/cppcore/Utils.h
index c064cb6a..ad7784ed 100644
--- a/efel/cppcore/Utils.h
+++ b/efel/cppcore/Utils.h
@@ -25,6 +25,8 @@
 #include <algorithm>
 #include <numeric>
 #include <vector>
+#include <sstream>
+#include <string>
 #include <utility>
 #include "EfelExceptions.h"
 
@@ -86,8 +88,9 @@ inline void
 efel_assert(bool assertion, const char *message, const char *file, const int line)
 {
   if(!assertion){
-    using std::string, std::to_string;
-    string errorMsg = "Assertion fired(" + string(file) + ":" + to_string(line) + "): " + string(message);
+    std::ostringstream os;
+    os << "Assertion fired(" << file << ":" << line << "): " << message;
+    std::string errorMsg = os.str();
     throw EfelAssertionError(errorMsg);
   }
 }