diff --git a/sources/core/args.h b/sources/core/args.h
index 878de73598b335a158d5c74bfa2990ece928f89e..3b9578925fdf7fbbe68c090d5ad374efdf4d8822 100644
--- a/sources/core/args.h
+++ b/sources/core/args.h
@@ -74,14 +74,14 @@ class arguments
 		float get_float(const std::string& key, float default_value = 0.0f) const
 		{
 			if(_map.count(key) > 0)
-				return atof(_map.at(key).c_str()) ;
+				return atof(_map.find(key)->second.c_str()) ;
 			else
 				return default_value ;
 		}
 		int get_int(const std::string& key, int default_value = 0) const
 		{
 			if(_map.count(key) > 0)
-				return atoi(_map.at(key).c_str()) ;
+				return atoi(_map.find(key)->second.c_str()) ;
 			else
 				return default_value ;
 		} 
@@ -90,7 +90,7 @@ class arguments
 			vec res(size);
 			if(_map.count(key) > 0)
 			{
-				std::string s = _map.at(key);
+				std::string s = _map.find(key)->second;
 				if(s[0] == '\[') // Is an array of type [a, b, c]
 				{
 					int i = 0;
diff --git a/sources/core/plugins_manager.cpp b/sources/core/plugins_manager.cpp
index cb11038875591c9d9b21faf2f97b687ca6b9b1cd..6e46bf4cd56e86dfafd6502394be2d129a1b36b6 100644
--- a/sources/core/plugins_manager.cpp
+++ b/sources/core/plugins_manager.cpp
@@ -130,7 +130,7 @@ function* plugins_manager::get_function(const std::string& n) const
 	}
 	else
 	{
-		return _functions.at(n) ;
+		return _functions.find(n)->second ;
 	}
 }
 data* plugins_manager::get_data(const std::string& n)     const 
@@ -143,7 +143,7 @@ data* plugins_manager::get_data(const std::string& n)     const
 	else
 	{
 		std::cout << "<<DEBUG>>  using \"" << n << "\" data loader" << std::endl ;
-		return _datas.at(n) ;
+		return _datas.find(n)->second ;
 	}
 }
 fitter* plugins_manager::get_fitter(const std::string& n)   const 
@@ -155,6 +155,6 @@ fitter* plugins_manager::get_fitter(const std::string& n)   const
 	else
 	{
 		std::cout << "<<DEBUG>>  using \"" <<  n << "\"" << std::endl ;
-		return _fitters.at(n) ;
+		return _fitters.find(n)->second ;
 	}
 }
diff --git a/sources/core/rational_function.cpp b/sources/core/rational_function.cpp
index cfc5b6cd5fca68aa635bd8a1eb80e4328f3a9593..d92803d8abaa62fa78a36f6baa95d2a028297e90 100644
--- a/sources/core/rational_function.cpp
+++ b/sources/core/rational_function.cpp
@@ -369,7 +369,7 @@ void rational_function::save_cpp(const std::string& filename, const arguments& a
 	file << "{" << std::endl;
 
 	file << "\tdouble p = ";
-	for(int i=0; i<a.size(); ++i)
+	for(unsigned int i=0; i<a.size(); ++i)
 	{
 		if(i > 0 && a[i] >= 0.0)
 		{
@@ -380,7 +380,7 @@ void rational_function::save_cpp(const std::string& filename, const arguments& a
 	file << 	";" << std::endl;
 
 	file << "\tdouble q = ";
-	for(int i=0; i<b.size(); ++i)
+	for(unsigned int i=0; i<b.size(); ++i)
 	{
 		if(i > 0)
 			file << " + ";
@@ -423,8 +423,8 @@ void rational_function::save_rational_function(const std::string& filename) cons
 	file << "#NQ " << b.size() / _nY << std::endl ;
 	file << "#BASIS poly" << std::endl ;
 
-	int np = a.size() / _nY ;
-	int nq = b.size() / _nX ;
+	unsigned int np = a.size() / _nY ;
+	unsigned int nq = b.size() / _nX ;
 	for(int k=0; k<_nY; ++k)
 	{
 		for(unsigned int i=0; i<np; ++i)