3 files changed, 14 insertions, 8 deletions
diff --git a/src/libmain/common-args.hh b/src/libmain/common-args.hh
index 2c0d71edd815..a4de3dccf0a5 100644
--- a/src/libmain/common-args.hh
+++ b/src/libmain/common-args.hh
@@ -12,7 +12,7 @@ struct MixCommonArgs : virtual Args
 
 struct MixDryRun : virtual Args
 {
-    bool dryRun;
+    bool dryRun = false;
 
     MixDryRun()
     {
@@ -20,4 +20,14 @@ struct MixDryRun : virtual Args
     }
 };
 
+struct MixJSON : virtual Args
+{
+    bool json = false;
+
+    MixJSON()
+    {
+        mkFlag(0, "json", "produce JSON output", &json);
+    }
+};
+
 }
diff --git a/src/nix/path-info.cc b/src/nix/path-info.cc
index 0f9a1125f2e9..30b193798f69 100644
--- a/src/nix/path-info.cc
+++ b/src/nix/path-info.cc
@@ -2,25 +2,24 @@
 #include "shared.hh"
 #include "store-api.hh"
 #include "json.hh"
+#include "common-args.hh"
 
 #include <iomanip>
 #include <algorithm>
 
 using namespace nix;
 
-struct CmdPathInfo : StorePathsCommand
+struct CmdPathInfo : StorePathsCommand, MixJSON
 {
     bool showSize = false;
     bool showClosureSize = false;
     bool showSigs = false;
-    bool json = false;
 
     CmdPathInfo()
     {
         mkFlag('s', "size", "print size of the NAR dump of each path", &showSize);
         mkFlag('S', "closure-size", "print sum size of the NAR dumps of the closure of each path", &showClosureSize);
         mkFlag(0, "sigs", "show signatures", &showSigs);
-        mkFlag(0, "json", "produce JSON output", &json);
     }
 
     std::string name() override
diff --git a/src/nix/show-config.cc b/src/nix/show-config.cc
index aade2adeace4..e354891a82e4 100644
--- a/src/nix/show-config.cc
+++ b/src/nix/show-config.cc
@@ -7,13 +7,10 @@
 
 using namespace nix;
 
-struct CmdShowConfig : Command
+struct CmdShowConfig : Command, MixJSON
 {
-    bool json = false;
-
     CmdShowConfig()
     {
-        mkFlag(0, "json", "produce JSON output", &json);
     }
 
     std::string name() override