diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 9c6aedfa5..7efa81a62 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1904,7 +1904,7 @@ void DerivationGoal::startBuilder()
             concatStringsSep(", ", parsedDrv->getRequiredSystemFeatures()),
             worker.store.printStorePath(drvPath),
             settings.thisSystem,
-            concatStringsSep(", ", settings.systemFeatures));
+            concatStringsSep<StringSet>(", ", settings.systemFeatures));
 
     if (drv->isBuiltin())
         preloadNSS();
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index b043feb0a..aacbe5e0b 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -741,12 +741,7 @@ std::string Store::showPaths(const StorePathSet & paths)
 
 string showPaths(const PathSet & paths)
 {
-    string s;
-    for (auto & i : paths) {
-        if (s.size() != 0) s += ", ";
-        s += "'" + i + "'";
-    }
-    return s;
+    return concatStringsSep(", ", quoteStrings(paths));
 }
 
 
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 012f1d071..52a1394f2 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1205,28 +1205,6 @@ template StringSet tokenizeString(std::string_view s, const string & separators)
 template vector<string> tokenizeString(std::string_view s, const string & separators);
 
 
-string concatStringsSep(const string & sep, const Strings & ss)
-{
-    string s;
-    for (auto & i : ss) {
-        if (s.size() != 0) s += sep;
-        s += i;
-    }
-    return s;
-}
-
-
-string concatStringsSep(const string & sep, const StringSet & ss)
-{
-    string s;
-    for (auto & i : ss) {
-        if (s.size() != 0) s += sep;
-        s += i;
-    }
-    return s;
-}
-
-
 string chomp(const string & s)
 {
     size_t i = s.find_last_not_of(" \n\r\t");
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 3bfebcd15..559ed4332 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -345,8 +345,26 @@ template<class C> C tokenizeString(std::string_view s, const string & separators
 
 /* Concatenate the given strings with a separator between the
    elements. */
-string concatStringsSep(const string & sep, const Strings & ss);
-string concatStringsSep(const string & sep, const StringSet & ss);
+template<class C>
+string concatStringsSep(const string & sep, const C & ss)
+{
+    string s;
+    for (auto & i : ss) {
+        if (s.size() != 0) s += sep;
+        s += i;
+    }
+    return s;
+}
+
+
+/* Add quotes around a collection of strings. */
+template<class C> Strings quoteStrings(const C & c)
+{
+    Strings res;
+    for (auto & s : c)
+        res.push_back("'" + s + "'");
+    return res;
+}
 
 
 /* Remove trailing whitespace from a string. */