diff --git a/src/vulnix/nix.py b/src/vulnix/nix.py
index 8c0eafc..ae30c73 100644
--- a/src/vulnix/nix.py
+++ b/src/vulnix/nix.py
@@ -59,11 +59,13 @@ def _call_nix(self, args):
                          'nix-command flakes'] + args)
         return call(['nix'] + args)
 
-    def _find_deriver(self, path, qpi_deriver=None):
+    def _find_deriver(self, path, qpi_deriver="undef"):
+        if not path or not qpi_deriver:
+            return None
         if path.endswith('.drv'):
             return path
         # Deriver from QueryPathInfo
-        if qpi_deriver is None:
+        if qpi_deriver == "undef":
             qpi_deriver = call(['nix-store', '-qd', path]).strip()
         _log.debug('qpi_deriver: %s', qpi_deriver)
         if qpi_deriver and qpi_deriver != 'unknown-deriver' and p.exists(
@@ -109,22 +111,24 @@ def add_path(self, path):
 
         if self.closure:
             for output in self._find_outputs(path):
-                for candidate in map(
-                    # We cannot use the `deriver` field directly because
-                    # like from `nix-store -qd` that path may not exist.
-                    # However, we know that if it is not present
-                    # the path has no deriver because it is a
-                    # derivation input source so we can skip it.
-                    lambda p: self._find_deriver(
-                                  p.get('path'),
-                                  qpi_deriver=p.get('deriver')
-                              ) if p.get('deriver') is not None else None,
-                    json.loads(
-                        self._call_nix(['path-info', '-r', '--json', output])
-                    )
-                ):
-                    if candidate is not None:
+                data = json.loads(self._call_nix(['path-info', '-r', '--json', output]))
+                if not data:
+                    continue
+                # 'nix path-info -r --json' can return two different json
+                # output format: https://github.com/NixOS/nix/pull/9242
+                if isinstance(data, dict):
+                    for outpath, info in data.items():
+                        drv = info.get('deriver')
+                        candidate = self._find_deriver(outpath, qpi_deriver=drv)
                         self.update(candidate)
+                elif isinstance(data, list):
+                    for info in data:
+                        outpath = info.get('path')
+                        drv = info.get('deriver')
+                        candidate = self._find_deriver(outpath, qpi_deriver=drv)
+                        self.update(candidate)
+                else:
+                    _log.warning("path-info for '%s' returned unexpected json", output)
         else:
             deriver = self._find_deriver(path)
             if self.requisites:
@@ -136,7 +140,7 @@ def add_path(self, path):
                 self.update(deriver)
 
     def update(self, drv_path):
-        if not drv_path.endswith('.drv'):
+        if not drv_path or not drv_path.endswith('.drv'):
             return
         try:
             drv_obj = load(drv_path)