diff --git a/src/libcmd/repl-interacter.cc b/src/libcmd/repl-interacter.cc
index 769935efa..4de335dd5 100644
--- a/src/libcmd/repl-interacter.cc
+++ b/src/libcmd/repl-interacter.cc
@@ -2,6 +2,8 @@
 
 #include <cstdio>
 
+#include <signal.h>
+
 #if USE_READLINE
 #include <readline/history.h>
 #include <readline/readline.h>
diff --git a/src/libexpr/eval-profiler.cc b/src/libexpr/eval-profiler.cc
index c72737f73..7053e4ec7 100644
--- a/src/libexpr/eval-profiler.cc
+++ b/src/libexpr/eval-profiler.cc
@@ -137,7 +137,7 @@ public:
         : state(state)
         , sampleInterval(period)
         , profileFd([&]() {
-            AutoCloseFD fd = toDescriptor(open(profileFile.c_str(), O_WRONLY | O_CREAT | O_TRUNC, 0660));
+            AutoCloseFD fd = toDescriptor(open(profileFile.string().c_str(), O_WRONLY | O_CREAT | O_TRUNC, 0660));
             if (!fd)
                 throw SysError("opening file %s", profileFile);
             return fd;
diff --git a/src/libutil/include/nix/util/unix-domain-socket.hh b/src/libutil/include/nix/util/unix-domain-socket.hh
index 6885d740b..3aaaddf82 100644
--- a/src/libutil/include/nix/util/unix-domain-socket.hh
+++ b/src/libutil/include/nix/util/unix-domain-socket.hh
@@ -80,7 +80,7 @@ void bind(Socket fd, const std::string & path);
 /**
  * Connect to a Unix domain socket.
  */
-void connect(Socket fd, const std::string & path);
+void connect(Socket fd, const std::filesystem::path & path);
 
 /**
  * Connect to a Unix domain socket.
diff --git a/src/libutil/logging.cc b/src/libutil/logging.cc
index a328a5c73..9b4ecbda8 100644
--- a/src/libutil/logging.cc
+++ b/src/libutil/logging.cc
@@ -324,7 +324,7 @@ std::unique_ptr<Logger> makeJSONLogger(const std::filesystem::path & path, bool
     AutoCloseFD fd =
         std::filesystem::is_socket(path)
         ? connect(path)
-        : toDescriptor(open(path.c_str(), O_CREAT | O_APPEND | O_WRONLY, 0644));
+        : toDescriptor(open(path.string().c_str(), O_CREAT | O_APPEND | O_WRONLY, 0644));
     if (!fd)
         throw SysError("opening log file %1%", path);
 
diff --git a/src/libutil/unix-domain-socket.cc b/src/libutil/unix-domain-socket.cc
index 0e8c21d66..2422caf14 100644
--- a/src/libutil/unix-domain-socket.cc
+++ b/src/libutil/unix-domain-socket.cc
@@ -29,7 +29,6 @@ AutoCloseFD createUnixDomainSocket()
     return fdSocket;
 }
 
-
 AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode)
 {
     auto fdSocket = nix::createUnixDomainSocket();
@@ -100,7 +99,6 @@ static void bindConnectProcHelper(
     }
 }
 
-
 void bind(Socket fd, const std::string & path)
 {
     unlink(path.c_str());
@@ -108,10 +106,9 @@ void bind(Socket fd, const std::string & path)
     bindConnectProcHelper("bind", ::bind, fd, path);
 }
 
-
-void connect(Socket fd, const std::string & path)
+void connect(Socket fd, const std::filesystem::path & path)
 {
-    bindConnectProcHelper("connect", ::connect, fd, path);
+    bindConnectProcHelper("connect", ::connect, fd, path.string());
 }
 
 AutoCloseFD connect(const std::filesystem::path & path)
diff --git a/src/libutil/windows/file-system.cc b/src/libutil/windows/file-system.cc
index a73fa223a..f31c913f1 100644
--- a/src/libutil/windows/file-system.cc
+++ b/src/libutil/windows/file-system.cc
@@ -1,4 +1,5 @@
 #include "nix/util/file-system.hh"
+#include "nix/util/logging.hh"
 
 #ifdef _WIN32
 namespace nix {
diff --git a/src/nix/formatter.cc b/src/nix/formatter.cc
index 627fb362c..212bb8d70 100644
--- a/src/nix/formatter.cc
+++ b/src/nix/formatter.cc
@@ -92,7 +92,7 @@ struct CmdFormatterRun : MixFormatter, MixJSON
         // Add the path to the flake as an environment variable. This enables formatters to format the entire flake even
         // if run from a subdirectory.
         StringMap env = getEnv();
-        env["PRJ_ROOT"] = flakeDir;
+        env["PRJ_ROOT"] = flakeDir.string();
 
         // Release our references to eval caches to ensure they are persisted to disk, because
         // we are about to exec out of this process without running C++ destructors.