diff --git a/src/hydra-eval-jobs/hydra-eval-jobs.cc b/src/hydra-eval-jobs/hydra-eval-jobs.cc
index acffe1d..53f2630 100644
--- a/src/hydra-eval-jobs/hydra-eval-jobs.cc
+++ b/src/hydra-eval-jobs/hydra-eval-jobs.cc
@@ -63,7 +63,7 @@ struct MyArgs : MixEvalArgs, MixCommonArgs
 
 static MyArgs myArgs;
 
-static std::string queryMetaStrings(EvalState & state, DrvInfo & drv, const string & name, const string & subAttribute)
+static std::string queryMetaStrings(EvalState & state, DrvInfo & drv, const std::string & name, const std::string & subAttribute)
 {
     Strings res;
     std::function<void(Value & v)> rec;
@@ -186,7 +186,7 @@ static void worker(
                     for (auto & i : context)
                         if (i.at(0) == '!') {
                             size_t index = i.find("!", 1);
-                            job["constituents"].push_back(string(i, index + 1));
+                            job["constituents"].push_back(std::string(i, index + 1));
                         }
 
                     state.forceList(*a->value, *a->pos);
diff --git a/src/hydra-queue-runner/hydra-queue-runner.cc b/src/hydra-queue-runner/hydra-queue-runner.cc
index 62eb572..a957bef 100644
--- a/src/hydra-queue-runner/hydra-queue-runner.cc
+++ b/src/hydra-queue-runner/hydra-queue-runner.cc
@@ -87,7 +87,7 @@ void State::parseMachines(const std::string & contents)
     }
 
     for (auto line : tokenizeString<Strings>(contents, "\n")) {
-        line = trim(string(line, 0, line.find('#')));
+        line = trim(std::string(line, 0, line.find('#')));
         auto tokens = tokenizeString<std::vector<std::string>>(line);
         if (tokens.size() < 3) continue;
         tokens.resize(8);
diff --git a/src/libhydra/db.hh b/src/libhydra/db.hh
index 7d5bdc5..00e8f40 100644
--- a/src/libhydra/db.hh
+++ b/src/libhydra/db.hh
@@ -18,7 +18,7 @@ struct Connection : pqxx::connection
         std::string upper_prefix = "DBI:Pg:";
 
         if (hasPrefix(s, lower_prefix) || hasPrefix(s, upper_prefix)) {
-            return concatStringsSep(" ", tokenizeString<Strings>(string(s, lower_prefix.size()), ";"));
+            return concatStringsSep(" ", tokenizeString<Strings>(std::string(s, lower_prefix.size()), ";"));
         }
 
         throw Error("$HYDRA_DBI does not denote a PostgreSQL database");
diff --git a/src/libhydra/hydra-config.hh b/src/libhydra/hydra-config.hh
index bc989f7..1688c27 100644
--- a/src/libhydra/hydra-config.hh
+++ b/src/libhydra/hydra-config.hh
@@ -17,7 +17,7 @@ struct HydraConfig
         if (hydraConfigFile && pathExists(*hydraConfigFile)) {
 
             for (auto line : tokenizeString<Strings>(readFile(*hydraConfigFile), "\n")) {
-                line = trim(string(line, 0, line.find('#')));
+                line = trim(std::string(line, 0, line.find('#')));
 
                 auto eq = line.find('=');
                 if (eq == std::string::npos) continue;