diff -up ./src/programs/pkcheck.c.ori ./src/programs/pkcheck.c
--- ./src/programs/pkcheck.c.ori	2021-12-17 11:56:55.336675787 +0100
+++ ./src/programs/pkcheck.c	2021-12-17 12:08:19.736029380 +0100
@@ -362,6 +362,12 @@ main (int argc, char *argv[])
   local_agent_handle = NULL;
   ret = 126;
 
+  if (argc < 1)
+    {
+      help();
+      exit(1);
+    }
+
   g_type_init ();
 
   details = polkit_details_new ();
diff -up ./src/programs/pkexec.c.ori ./src/programs/pkexec.c
--- ./src/programs/pkexec.c.ori	2021-12-17 11:55:12.686171757 +0100
+++ ./src/programs/pkexec.c	2021-12-17 11:56:55.336675787 +0100
@@ -490,6 +490,17 @@ main (int argc, char *argv[])
   pid_t pid_of_caller;
   gpointer local_agent_handle;
 
+
+  /*
+   * If 'pkexec' is called wrong, just show help and bail out.
+   */
+  if (argc<1)
+    {
+      clearenv();
+      usage(argc, argv);
+      exit(1);
+    }
+
   ret = 127;
   authority = NULL;
   subject = NULL;
@@ -601,7 +612,15 @@ main (int argc, char *argv[])
           goto out;
         }
       g_free (path);
-      argv[n] = path = s;
+      path = s;
+
+      /* argc<2 and pkexec runs just shell, argv is guaranteed to be null-terminated.
+       * /-less shell shouldn't happen, but let's be defensive and don't write to null-termination
+       */
+      if (argv[n] != NULL)
+      {
+        argv[n] = path;
+      }
     }
   if (access (path, F_OK) != 0)
     {