diff --git a/src/crlf.cc b/src/crlf.cc
new file mode 100644
index 0000000..1d9a3a9
--- /dev/null
+++ b/src/crlf.cc
@@ -0,0 +1,26 @@
+#include "crlf.hh"
+
+namespace pEp
+{
+
+std::string operator""_CRLF(const char* str, size_t length)
+{
+    static const std::string CRLF{"\r\n"};
+
+    std::string ret;
+    ret.reserve(length + ((length+29)/30) + 2 ); // rough guess for average line length of 30.
+    const char* end = str + length;
+    
+    // N.B.: Loop could be more optimized, but not necessary because it is only used for string literals.
+    for(; str != end; ++str)
+    {
+        if(*str == '\n')
+            ret += CRLF;
+        else
+            ret += *str;
+    }
+    
+    return ret;
+}
+
+} // end of namespace pEp
diff --git a/src/crlf.hh b/src/crlf.hh
new file mode 100644
index 0000000..8b1b383
--- /dev/null
+++ b/src/crlf.hh
@@ -0,0 +1,19 @@
+// This file is under GNU General Public License 3.0
+// see LICENSE.txt
+
+#ifndef LIBPEPDATATYPES_CRLF_HH
+#define LIBPEPDATATYPES_CRLF_HH
+
+#include <string>
+
+namespace pEp
+{
+    // creates a string where \n ("linefeed" a.k.a. LF) are replaced
+    // by \r\n ("carriage return + linefeed" a.k.a. CRLF).
+    // Useful to define strings in NET-ASCII or Net-Unicode (RFC5198) format
+    // from string literals. 
+    std::string operator""_CRLF(const char* str, size_t length);
+
+} // end of namespace pEp
+
+#endif // LIBPEPDATATYPES_CRLF_HH