diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 7e27e95c2..5baaff3e9 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -229,11 +229,17 @@ LegacyArgs::LegacyArgs(const std::string & programName,
     intSettingAlias(0, "max-silent-time", "Number of seconds of silence before a build is killed.", "max-silent-time");
     intSettingAlias(0, "timeout", "Number of seconds before a build is killed.", "timeout");
 
-    mkFlag(0, "readonly-mode", "Do not write to the Nix store.",
-        &settings.readOnlyMode);
+    addFlag({
+        .longName = "readonly-mode",
+        .description = "Do not write to the Nix store.",
+        .handler = {&settings.readOnlyMode, true},
+    });
 
-    mkFlag(0, "no-gc-warning", "Disable warnings about not using `--add-root`.",
-        &gcWarning, false);
+    addFlag({
+        .longName = "no-gc-warning",
+        .description = "Disable warnings about not using `--add-root`.",
+        .handler = {&gcWarning, true},
+    });
 
     addFlag({
         .longName = "store",
diff --git a/src/libutil/args.hh b/src/libutil/args.hh
index b1020b101..42d8515ef 100644
--- a/src/libutil/args.hh
+++ b/src/libutil/args.hh
@@ -135,27 +135,6 @@ public:
 
     void addFlag(Flag && flag);
 
-    /* Helper functions for constructing flags / positional
-       arguments. */
-
-    void mkFlag(char shortName, const std::string & name,
-        const std::string & description, bool * dest)
-    {
-        mkFlag(shortName, name, description, dest, true);
-    }
-
-    template<class T>
-    void mkFlag(char shortName, const std::string & longName, const std::string & description,
-        T * dest, const T & value)
-    {
-        addFlag({
-            .longName = longName,
-            .shortName = shortName,
-            .description = description,
-            .handler = {[=]() { *dest = value; }}
-        });
-    }
-
     void expectArgs(ExpectedArg && arg)
     {
         expectedArgs.emplace_back(std::move(arg));
diff --git a/src/nix/eval.cc b/src/nix/eval.cc
index b5049ac65..65d61e005 100644
--- a/src/nix/eval.cc
+++ b/src/nix/eval.cc
@@ -18,7 +18,11 @@ struct CmdEval : MixJSON, InstallableCommand
 
     CmdEval()
     {
-        mkFlag(0, "raw", "Print strings without quotes or escaping.", &raw);
+        addFlag({
+            .longName = "raw",
+            .description = "Print strings without quotes or escaping.",
+            .handler = {&raw, true},
+        });
 
         addFlag({
             .longName = "apply",
diff --git a/src/nix/hash.cc b/src/nix/hash.cc
index 79d506ace..4535e4ab0 100644
--- a/src/nix/hash.cc
+++ b/src/nix/hash.cc
@@ -19,18 +19,41 @@ struct CmdHashBase : Command
 
     CmdHashBase(FileIngestionMethod mode) : mode(mode)
     {
-        mkFlag(0, "sri", "Print the hash in SRI format.", &base, SRI);
-        mkFlag(0, "base64", "Print the hash in base-64 format.", &base, Base64);
-        mkFlag(0, "base32", "Print the hash in base-32 (Nix-specific) format.", &base, Base32);
-        mkFlag(0, "base16", "Print the hash in base-16 format.", &base, Base16);
+        addFlag({
+            .longName = "sri",
+            .description = "Print the hash in SRI format.",
+            .handler = {&base, SRI},
+        });
+
+        addFlag({
+            .longName = "base64",
+            .description = "Print the hash in base-64 format.",
+            .handler = {&base, Base64},
+        });
+
+        addFlag({
+            .longName = "base32",
+            .description = "Print the hash in base-32 (Nix-specific) format.",
+            .handler = {&base, Base32},
+        });
+
+        addFlag({
+            .longName = "base16",
+            .description = "Print the hash in base-16 format.",
+            .handler = {&base, Base16},
+        });
+
         addFlag(Flag::mkHashTypeFlag("type", &ht));
+
         #if 0
-        mkFlag()
-            .longName("modulo")
-            .description("Compute the hash modulo specified the string.")
-            .labels({"modulus"})
-            .dest(&modulus);
-        #endif
+        addFlag({
+            .longName = "modulo",
+            .description = "Compute the hash modulo the specified string.",
+            .labels = {"modulus"},
+            .handler = {&modulus},
+        });
+        #endif\
+
         expectArgs({
             .label = "paths",
             .handler = {&paths},
diff --git a/src/nix/ls.cc b/src/nix/ls.cc
index c0b1ecb32..c1dc9a95b 100644
--- a/src/nix/ls.cc
+++ b/src/nix/ls.cc
@@ -17,9 +17,26 @@ struct MixLs : virtual Args, MixJSON
 
     MixLs()
     {
-        mkFlag('R', "recursive", "List subdirectories recursively.", &recursive);
-        mkFlag('l', "long", "Show detailed file information.", &verbose);
-        mkFlag('d', "directory", "Show directories rather than their contents.", &showDirectory);
+        addFlag({
+            .longName = "recursive",
+            .shortName = 'R',
+            .description = "List subdirectories recursively.",
+            .handler = {&recursive, true},
+        });
+
+        addFlag({
+            .longName = "long",
+            .shortName = 'l',
+            .description = "Show detailed file information.",
+            .handler = {&verbose, true},
+        });
+
+        addFlag({
+            .longName = "directory",
+            .shortName = 'd',
+            .description = "Show directories rather than their contents.",
+            .handler = {&showDirectory, true},
+        });
     }
 
     void listText(ref<FSAccessor> accessor)
diff --git a/src/nix/path-info.cc b/src/nix/path-info.cc
index 0fa88f1bf..518cd5568 100644
--- a/src/nix/path-info.cc
+++ b/src/nix/path-info.cc
@@ -18,10 +18,32 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
 
     CmdPathInfo()
     {
-        mkFlag('s', "size", "Print the size of the NAR serialisation of each path.", &showSize);
-        mkFlag('S', "closure-size", "Print the sum of the sizes of the NAR serialisations of the closure of each path.", &showClosureSize);
-        mkFlag('h', "human-readable", "With `-s` and `-S`, print sizes in a human-friendly format such as `5.67G`.", &humanReadable);
-        mkFlag(0, "sigs", "Show signatures.", &showSigs);
+        addFlag({
+            .longName = "size",
+            .shortName = 's',
+            .description = "Print the size of the NAR serialisation of each path.",
+            .handler = {&showSize, true},
+        });
+
+        addFlag({
+            .longName = "closure-size",
+            .shortName = 'S',
+            .description = "Print the sum of the sizes of the NAR serialisations of the closure of each path.",
+            .handler = {&showClosureSize, true},
+        });
+
+        addFlag({
+            .longName = "human-readable",
+            .shortName = 'h',
+            .description = "With `-s` and `-S`, print sizes in a human-friendly format such as `5.67G`.",
+            .handler = {&humanReadable, true},
+        });
+
+        addFlag({
+            .longName = "sigs",
+            .description = "Show signatures.",
+            .handler = {&showSigs, true},
+        });
     }
 
     std::string description() override
diff --git a/src/nix/verify.cc b/src/nix/verify.cc
index 9b04e032a..1721c7f16 100644
--- a/src/nix/verify.cc
+++ b/src/nix/verify.cc
@@ -18,8 +18,17 @@ struct CmdVerify : StorePathsCommand
 
     CmdVerify()
     {
-        mkFlag(0, "no-contents", "Do not verify the contents of each store path.", &noContents);
-        mkFlag(0, "no-trust", "Do not verify whether each store path is trusted.", &noTrust);
+        addFlag({
+            .longName = "no-contents",
+            .description = "Do not verify the contents of each store path.",
+            .handler = {&noContents, true},
+        });
+
+        addFlag({
+            .longName = "no-trust",
+            .description = "Do not verify whether each store path is trusted.",
+            .handler = {&noTrust, true},
+        });
 
         addFlag({
             .longName = "substituter",