diff --git a/spot/ltsmin/ltsmin.cc b/spot/ltsmin/ltsmin.cc
index 32e3d1431..a6cebb285 100644
--- a/spot/ltsmin/ltsmin.cc
+++ b/spot/ltsmin/ltsmin.cc
@@ -38,6 +38,8 @@
 #include <spot/misc/intvcomp.hh>
 #include <spot/misc/intvcmp2.hh>
 
+using namespace std::string_literals;
+
 namespace spot
 {
   namespace
@@ -972,15 +974,15 @@ namespace spot
         }
       else
         {
-          throw std::runtime_error(std::string("Unknown extension '")
-                                   + ext + "'.  Use '.prom', '.pm', '.pml', "
+          throw std::runtime_error("Unknown extension '"s + ext +
+                                   "'.  Use '.prom', '.pm', '.pml', "
                                    "'.dve', '.dve2C', '.gal', '.gal2C' or "
                                    "'.prom.spins'.");
         }
 
       struct stat s;
       if (stat(filename.c_str(), &s) != 0)
-        throw std::runtime_error(std::string("Cannot open ") + filename);
+        throw std::runtime_error("Cannot open "s + filename);
 
       filename += compiled_ext;
 
@@ -998,7 +1000,7 @@ namespace spot
 
       int res = system(command.c_str());
       if (res)
-        throw std::runtime_error(std::string("Execution of '")
+        throw std::runtime_error("Execution of '"s
                                  + command.c_str() + "' returned exit code "
                                  + std::to_string(WEXITSTATUS(res)));
     }
@@ -1029,7 +1031,7 @@ namespace spot
       {
         std::string lt_error = lt_dlerror();
         lt_dlexit();
-        throw std::runtime_error(std::string("Failed to load '")
+        throw std::runtime_error("Failed to load '"s
                                  + file + "'.\n" + lt_error);
       }
 
@@ -1046,7 +1048,7 @@ namespace spot
         // assume they can for POSIX).
         *reinterpret_cast<void**>(dst) = lt_dlsym(h, name);
         if (dst == nullptr)
-          throw std::runtime_error(std::string("Failed to resolve symbol '")
+          throw std::runtime_error("Failed to resolve symbol '"s
                                    + name + "' in '" + file + "'.");
       };
 
diff --git a/spot/misc/tmpfile.cc b/spot/misc/tmpfile.cc
index 7e9108aea..6eda6abff 100644
--- a/spot/misc/tmpfile.cc
+++ b/spot/misc/tmpfile.cc
@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2013, 2015, 2017 Laboratoire de Recherche et
+// Copyright (C) 2013, 2015, 2017, 2018 Laboratoire de Recherche et
 // Développement de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
@@ -24,6 +24,8 @@
 #include <unistd.h>
 #include <string.h>
 
+using namespace std::string_literals;
+
 namespace spot
 {
   namespace
@@ -73,7 +75,7 @@ namespace spot
           fd = mkstemp(*name);
         }
       if (fd < 0)
-        throw std::runtime_error(std::string("failed to create ") + *name);
+        throw std::runtime_error("failed to create "s + *name);
       return fd;
     }
   }
@@ -109,7 +111,7 @@ namespace spot
     if (fd_ < 0)
       return;
     if (::close(fd_))
-      throw std::runtime_error(std::string("failed to close ") + name_);
+      throw std::runtime_error("failed to close "s + name_);
     fd_ = -1;
   }
 
@@ -119,7 +121,7 @@ namespace spot
     char* name;
     int fd = create_temporary_file(prefix, suffix, &name);
     if (close(fd))
-      throw std::runtime_error(std::string("failed to close ") + name);
+      throw std::runtime_error("failed to close "s + name);
     auto cp = to_clean.insert(to_clean.end(), nullptr);
     *cp = new temporary_file(name, cp);
     return *cp;
diff --git a/spot/parseaut/parseaut.yy b/spot/parseaut/parseaut.yy
index 6239bbaa0..bcb3685e3 100644
--- a/spot/parseaut/parseaut.yy
+++ b/spot/parseaut/parseaut.yy
@@ -43,6 +43,8 @@
 #include <spot/tl/parse.hh>
 #include <spot/twaalgos/alternation.hh>
 
+using namespace std::string_literals;
+
 #ifndef HAVE_STRVERSCMP
 // If the libc does not have this, a version is compiled in lib/.
 extern "C" int strverscmp(const char *s1, const char *s2);
@@ -877,11 +879,10 @@ properties: | properties IDENTIFIER
 		if (pos.first->second.val != val)
 		  {
 		    std::ostringstream out(std::ios_base::ate);
-		    error(@2, std::string("'properties: ")
-			  + (val ? "" : "!") + *$2 + "' contradicts...");
+		    error(@2, "'properties: "s + (val ? "" : "!")
+                          + *$2 + "' contradicts...");
 		    error(pos.first->second.loc,
-			  std::string("... 'properties: ")
-                          + (val ? "!" : "") + *$2
+			  "... 'properties: "s + (val ? "!" : "") + *$2
 			  + "' previously given here.");
 		  }
 		delete $2;
@@ -894,11 +895,9 @@ properties: | properties IDENTIFIER
 		if (pos.first->second.val)
 		  {
 		    std::ostringstream out(std::ios_base::ate);
-		    error(loc, std::string("'properties: !")
-			  + *$3 + "' contradicts...");
-		    error(pos.first->second.loc,
-			  std::string("... 'properties: ") + *$3
-			  + "' previously given here.");
+		    error(loc, "'properties: !"s + *$3 + "' contradicts...");
+		    error(pos.first->second.loc, "... 'properties: "s + *$3
+                          + "' previously given here.");
 		  }
 		delete $3;
 	      }
@@ -1058,7 +1057,7 @@ acceptance-cond: IDENTIFIER '(' acc-set ')'
                          }
                        else
                          {
-                           error(@1, std::string("unknown acceptance '") + *$1
+                           error(@1, "unknown acceptance '"s + *$1
                                  + "', expected Fin or Inf");
                            $$ = new spot::acc_cond::acc_code;
                          }
@@ -1837,9 +1836,8 @@ nc-one-ident: IDENTIFIER ':'
       auto r = res.labels.insert(std::make_pair(*$1, @1));
       if (!r.second)
 	{
-	  error(@1, std::string("redefinition of ") + *$1 + "...");
-	  error(r.first->second, std::string("... ")  + *$1
-		+ " previously defined here");
+	  error(@1, "redefinition of "s + *$1 + "...");
+	  error(r.first->second, "... "s + *$1 + " previously defined here");
 	}
       $$ = $1;
     }
@@ -2507,7 +2505,7 @@ namespace spot
     : filename_(name), opts_(opt)
   {
     if (hoayyopen(name, &scanner_))
-      throw std::runtime_error(std::string("Cannot open file ") + name);
+      throw std::runtime_error("Cannot open file "s + name);
   }
   catch (...)
   {
@@ -2522,7 +2520,7 @@ namespace spot
     : filename_(name), opts_(opt)
   {
     if (hoayyopen(fd, &scanner_))
-      throw std::runtime_error(std::string("Cannot open file ") + name);
+      throw std::runtime_error("Cannot open file "s + name);
   }
   catch (...)
   {
diff --git a/spot/taalgos/dot.cc b/spot/taalgos/dot.cc
index 39e69e683..91b6065a9 100644
--- a/spot/taalgos/dot.cc
+++ b/spot/taalgos/dot.cc
@@ -27,6 +27,8 @@
 #include <cstdlib>
 #include <cstring>
 
+using namespace std::string_literals;
+
 namespace spot
 {
   namespace
@@ -55,7 +57,7 @@ namespace spot
                 // Prevent infinite recursions...
                 if (orig == def.c_str())
                   throw std::runtime_error
-                    (std::string("SPOT_DOTDEFAULT should not contain '.'"));
+                    ("SPOT_DOTDEFAULT should not contain '.'");
                 if (!def.empty())
                   parse_opts(def.c_str());
                 break;
@@ -85,12 +87,12 @@ namespace spot
             case 'f':
               if (*options != '(')
                 throw std::runtime_error
-                  (std::string("invalid font specification for dotty()"));
+                  ("invalid font specification for dotty()");
               {
                 auto* end = strchr(++options, ')');
                 if (!end)
                   throw std::runtime_error
-                    (std::string("invalid font specification for dotty()"));
+                    ("invalid font specification for dotty()");
                 opt_font_ = std::string(options, end - options);
                 options = end + 1;
               }
@@ -128,8 +130,7 @@ namespace spot
               // SPOT_DEFAULT would be annoying.
               break;
             default:
-              throw std::runtime_error
-                (std::string("unknown option for dotty(): ") + c);
+              throw std::runtime_error("unknown option for dotty(): "s + c);
             }
       }
 
diff --git a/spot/tl/hierarchy.cc b/spot/tl/hierarchy.cc
index 7b9716f5a..ec89ca14d 100644
--- a/spot/tl/hierarchy.cc
+++ b/spot/tl/hierarchy.cc
@@ -32,6 +32,7 @@
 #include <spot/twaalgos/totgba.hh>
 #include <spot/twaalgos/cobuchi.hh>
 
+using namespace std::string_literals;
 
 namespace spot
 {
@@ -460,7 +461,7 @@ namespace spot
           goto break2;
         default:
           throw std::runtime_error
-            (std::string("nesting_depth(): unknown operator '") + c + '\'');
+            ("nesting_depth(): unknown operator '"s + c + '\'');
         }
   break2:
     if (want_nnf)
diff --git a/spot/tl/unabbrev.cc b/spot/tl/unabbrev.cc
index e0164a5ce..c7bc01924 100644
--- a/spot/tl/unabbrev.cc
+++ b/spot/tl/unabbrev.cc
@@ -21,6 +21,8 @@
 #include "config.h"
 #include <spot/tl/unabbrev.hh>
 
+using namespace std::string_literals;
+
 namespace spot
 {
   unabbreviator::unabbreviator(const char* opt)
@@ -61,9 +63,7 @@ namespace spot
           re_some_bool_ = true;
           break;
         default:
-          throw std::runtime_error
-            (std::string("unknown unabbreviation option: ")
-             + c);
+          throw std::runtime_error("unknown unabbreviation option: "s + c);
         }
   }
 
diff --git a/spot/twa/acc.cc b/spot/twa/acc.cc
index 210bc4721..f1228b6c8 100644
--- a/spot/twa/acc.cc
+++ b/spot/twa/acc.cc
@@ -30,6 +30,8 @@
 #include <spot/misc/minato.hh>
 #include <spot/misc/random.hh>
 
+using namespace std::string_literals;
+
 namespace spot
 {
   void acc_cond::report_too_many_sets()
@@ -1654,7 +1656,7 @@ namespace spot
             break;
           default:
             throw std::runtime_error
-              (std::string("unknown option for acc_cond::name(): ") + c);
+              ("unknown option for acc_cond::name(): "s + c);
           }
 
     std::ostringstream os;
diff --git a/spot/twa/twagraph.cc b/spot/twa/twagraph.cc
index db5ce6976..97a9908ec 100644
--- a/spot/twa/twagraph.cc
+++ b/spot/twa/twagraph.cc
@@ -26,6 +26,8 @@
 #include <vector>
 #include <deque>
 
+using namespace std::string_literals;
+
 namespace spot
 {
 
@@ -791,9 +793,8 @@ namespace spot
               want_properties = true;
               break;
             default:
-              throw std::runtime_error(std::string("dump_storage_as_dow(): "
-                                                   "unsupported option '")
-                                       + opt[-1] +"'");
+              throw std::runtime_error
+                ("dump_storage_as_dow(): unsupported option '"s + opt[-1] +"'");
             }
       }
 
diff --git a/spot/twaalgos/dot.cc b/spot/twaalgos/dot.cc
index 3ee7174d1..eed5688f7 100644
--- a/spot/twaalgos/dot.cc
+++ b/spot/twaalgos/dot.cc
@@ -39,6 +39,7 @@
 #include <ctype.h>
 #include <utility>
 
+using namespace std::string_literals;
 
 namespace spot
 {
@@ -176,7 +177,7 @@ namespace spot
                 // Prevent infinite recursions...
                 if (orig == def.c_str())
                   throw std::runtime_error
-                    (std::string("SPOT_DOTDEFAULT should not contain '.'"));
+                    ("SPOT_DOTDEFAULT should not contain '.'");
                 if (!def.empty())
                   parse_opts(def.c_str());
                 break;
@@ -312,7 +313,7 @@ namespace spot
               break;
             default:
               throw std::runtime_error
-                (std::string("unknown option for print_dot(): ") + c);
+                ("unknown option for print_dot(): "s + c);
             }
         if (opt_color_sets_ && !opt_latex_)
           opt_html_labels_ = true;
diff --git a/spot/twaalgos/hoa.cc b/spot/twaalgos/hoa.cc
index a992644cb..0a97c0f75 100644
--- a/spot/twaalgos/hoa.cc
+++ b/spot/twaalgos/hoa.cc
@@ -32,6 +32,8 @@
 #include <spot/tl/formula.hh>
 #include <spot/kripke/fairkripke.hh>
 
+using namespace std::string_literals;
+
 namespace spot
 {
   namespace
@@ -318,8 +320,7 @@ namespace spot
               verbose = true;
               break;
             default:
-              throw std::runtime_error
-                (std::string("unknown option for print_hoa(): ") + c);
+              throw std::runtime_error("unknown option for print_hoa(): "s + c);
             }
         }
 
diff --git a/spot/twaalgos/lbtt.cc b/spot/twaalgos/lbtt.cc
index f7a0dda7f..70750eaff 100644
--- a/spot/twaalgos/lbtt.cc
+++ b/spot/twaalgos/lbtt.cc
@@ -31,6 +31,8 @@
 #include "spot/priv/accmap.hh"
 #include <spot/tl/print.hh>
 
+using namespace std::string_literals;
+
 namespace spot
 {
   namespace
@@ -142,8 +144,7 @@ namespace spot
           sba = false;
           break;
         default:
-          throw std::runtime_error
-            (std::string("unknown option for print_lbtt(): ") + c);
+          throw std::runtime_error("unknown option for print_lbtt(): "s + c);
         }
 
     lbtt_bfs b(g, os, sba);
diff --git a/spot/twaalgos/neverclaim.cc b/spot/twaalgos/neverclaim.cc
index bd838f436..674cfe49a 100644
--- a/spot/twaalgos/neverclaim.cc
+++ b/spot/twaalgos/neverclaim.cc
@@ -29,6 +29,8 @@
 #include <spot/tl/print.hh>
 #include <spot/twa/formula2bdd.hh>
 
+using namespace std::string_literals;
+
 namespace spot
 {
   namespace
@@ -61,8 +63,7 @@ namespace spot
                 break;
               default:
                 throw std::runtime_error
-                  (std::string("unknown option for print_never_claim(): ")
-                   + c);
+                  ("unknown option for print_never_claim(): "s + c);
               }
       }
 
diff --git a/spot/twaalgos/strength.cc b/spot/twaalgos/strength.cc
index 42cc94251..6e39b06e5 100644
--- a/spot/twaalgos/strength.cc
+++ b/spot/twaalgos/strength.cc
@@ -23,6 +23,8 @@
 #include <spot/twaalgos/isweakscc.hh>
 #include <spot/twaalgos/mask.hh>
 
+using namespace std::string_literals;
+
 namespace spot
 {
   namespace
@@ -206,7 +208,7 @@ namespace spot
   {
     if (keep_opt == nullptr || *keep_opt == 0)
       throw std::runtime_error
-        (std::string("option for decompose_scc() should not be empty"));
+        ("option for decompose_scc() should not be empty");
 
     enum strength {
       Ignore = 0,
@@ -247,7 +249,7 @@ namespace spot
             if ((long unsigned) scc >= n)
               {
                 throw std::runtime_error
-                  (std::string("decompose_scc(): there is no SCC ")
+                  ("decompose_scc(): there is no SCC "s
                    + std::to_string(scc) + " in this automaton");
               }
             keep_opt = endptr;
@@ -272,7 +274,7 @@ namespace spot
             if (j != scc + 1)
               {
                 throw std::runtime_error
-                  (std::string("decompose_scc(): there is no SCC 'a")
+                  ("decompose_scc(): there is no SCC 'a"s
                    + std::to_string(scc) + "' in this automaton");
               }
             keep_opt = endptr;
@@ -289,7 +291,7 @@ namespace spot
           break;
         default:
           throw std::runtime_error
-            (std::string("unknown option for decompose_scc(): ") + c);
+            ("unknown option for decompose_scc(): "s + c);
         }
 
     auto p = aut->acc().unsat_mark();
diff --git a/spot/twaalgos/word.cc b/spot/twaalgos/word.cc
index cd117d898..ce5bd5861 100644
--- a/spot/twaalgos/word.cc
+++ b/spot/twaalgos/word.cc
@@ -25,6 +25,8 @@
 #include <spot/tl/simplify.hh>
 #include <spot/tl/apcollect.hh>
 
+using namespace std::string_literals;
+
 namespace spot
 {
   twa_word::twa_word(const twa_run_ptr& run)
@@ -185,7 +187,7 @@ namespace spot
       };
 
     // Parse the prefix part. Can be empty.
-    while (word.substr(i, 6) != std::string("cycle{"))
+    while (word.substr(i, 6) != "cycle{"s)
       {
         ind = skip_next_formula(word, i);
         if (ind == std::string::npos)