diff --git a/src/libutil/fmt.cc b/src/libutil/fmt.cc
index 914fb62b2..3dd93d73e 100644
--- a/src/libutil/fmt.cc
+++ b/src/libutil/fmt.cc
@@ -1,13 +1,20 @@
+#include "fmt.hh"
+
 #include <regex>
 
 namespace nix {
 
-std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches, std::string prefix, std::string postfix) {
+std::string hiliteMatches(
+    std::string_view s,
+    std::vector<std::smatch> matches,
+    std::string_view prefix,
+    std::string_view postfix)
+{
     // Avoid copy on zero matches
     if (matches.size() == 0)
-        return s;
+        return (std::string) s;
 
-    std::sort(matches.begin(), matches.end(), [](const auto &a, const auto &b) {
+    std::sort(matches.begin(), matches.end(), [](const auto & a, const auto & b) {
         return a.position() < b.position();
     });
 
@@ -20,10 +27,10 @@ std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches
         out.append(s.substr(last_end, m.position() - last_end));
         // Merge continous matches
         ssize_t end = start + m.length();
-        while(++it != matches.end() && (*it).position() <= end) {
+        while (++it != matches.end() && (*it).position() <= end) {
             auto n = *it;
             ssize_t nend = start + (n.position() - start + n.length());
-            if(nend > end)
+            if (nend > end)
                 end = nend;
         }
         out.append(prefix);
@@ -31,6 +38,7 @@ std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches
         out.append(postfix);
         last_end = end;
     }
+
     out.append(s.substr(last_end));
     return out;
 }
diff --git a/src/libutil/fmt.hh b/src/libutil/fmt.hh
index 1f81bfcfb..a7126fb65 100644
--- a/src/libutil/fmt.hh
+++ b/src/libutil/fmt.hh
@@ -156,12 +156,15 @@ inline hintformat hintfmt(std::string plain_string)
     return hintfmt("%s", normaltxt(plain_string));
 }
 
-/**
- * Highlight all the given matches in the given string `s` by wrapping them
- * between `prefix` and `postfix`.
- *
- * If some matches overlap, then their union will be wrapped rather than the
- * individual matches.
- */
-std::string hiliteMatches(const std::string &s, std::vector<std::smatch> matches, std::string prefix, std::string postfix);
+/* Highlight all the given matches in the given string `s` by wrapping
+   them between `prefix` and `postfix`.
+
+   If some matches overlap, then their union will be wrapped rather
+   than the individual matches. */
+std::string hiliteMatches(
+    std::string_view s,
+    std::vector<std::smatch> matches,
+    std::string_view prefix,
+    std::string_view postfix);
+
 }
diff --git a/src/nix/search.cc b/src/nix/search.cc
index 0d10d8c2e..e9307342c 100644
--- a/src/nix/search.cc
+++ b/src/nix/search.cc
@@ -106,19 +106,19 @@ struct CmdSearch : InstallableCommand, MixJSON
 
                     for (auto & regex : regexes) {
                         found = false;
-                        auto add_all = [&found](std::sregex_iterator it, std::vector<std::smatch>& vec){
+                        auto addAll = [&found](std::sregex_iterator it, std::vector<std::smatch> & vec) {
                             const auto end = std::sregex_iterator();
-                            while(it != end) {
+                            while (it != end) {
                                 vec.push_back(*it++);
                                 found = true;
                             }
                         };
 
-                        add_all(std::sregex_iterator(attrPath2.begin(), attrPath2.end(), regex), attrPathMatches);
-                        add_all(std::sregex_iterator(name.name.begin(), name.name.end(), regex), nameMatches);
-                        add_all(std::sregex_iterator(description.begin(), description.end(), regex), descriptionMatches);
+                        addAll(std::sregex_iterator(attrPath2.begin(), attrPath2.end(), regex), attrPathMatches);
+                        addAll(std::sregex_iterator(name.name.begin(), name.name.end(), regex), nameMatches);
+                        addAll(std::sregex_iterator(description.begin(), description.end(), regex), descriptionMatches);
 
-                        if(!found)
+                        if (!found)
                             break;
                     }