diff --git a/src/filesystem.cc b/src/filesystem.cc
index 4a05944..3a39fac 100644
--- a/src/filesystem.cc
+++ b/src/filesystem.cc
@@ -59,12 +59,15 @@ namespace {
 
 class RealFile : public File {
  public:
-  explicit RealFile(int fd) : fd_(fd) {}
+  RealFile(re2::StringPiece name, int fd)
+      : name_(name.data(), name.size()), fd_(fd) {}
   RealFile(const RealFile &) = delete;
   void operator=(const RealFile &) = delete;
 
   ~RealFile() final { Close(); }
 
+  const std::string &name() const { return name_; }
+
   int Access(const char *path, int mode, int flags) final {
     return faccessat(fd_, path, mode, flags) < 0 ? errno : 0;
   }
@@ -106,7 +109,7 @@ class RealFile : public File {
     if (ret < 0) {
       return errno;
     }
-    f->reset(new RealFile(ret));
+    f->reset(new RealFile(StrCat(name_, "/", path), ret));
     return 0;
   }
 
@@ -145,6 +148,7 @@ class RealFile : public File {
   }
 
  private:
+  std::string name_;
   int fd_ = -1;
 };
 
@@ -186,7 +190,7 @@ class RealFilesystem : public Filesystem {
     if (ret < 0) {
       return errno;
     }
-    f->reset(new RealFile(ret));
+    f->reset(new RealFile(path, ret));
     return 0;
   }
 
diff --git a/src/filesystem.h b/src/filesystem.h
index bc55ffa..ab30b55 100644
--- a/src/filesystem.h
+++ b/src/filesystem.h
@@ -58,6 +58,9 @@ class File {
   // Close the file, ignoring the result.
   virtual ~File() {}
 
+  // A name for the file (typically assigned at open time).
+  virtual const std::string &name() const = 0;
+
   // faccessat(), returning 0 on success or errno>0 on failure.
   virtual int Access(const char *path, int mode, int flags) = 0;
 
@@ -95,6 +98,7 @@ class File {
 
 class MockFile : public File {
  public:
+  MOCK_CONST_METHOD0(name, const std::string &());
   MOCK_METHOD3(Access, int(const char *, int, int));
   MOCK_METHOD0(Close, int());
 
diff --git a/src/recording.cc b/src/recording.cc
index 04bd751..afd26e8 100644
--- a/src/recording.cc
+++ b/src/recording.cc
@@ -143,7 +143,8 @@ bool SampleFileWriter::Open(const char *filename, std::string *error_message) {
   int ret =
       parent_dir_->Open(filename, O_WRONLY | O_CREAT | O_EXCL, 0600, &file_);
   if (ret != 0) {
-    *error_message = StrCat("open ", filename, ": ", strerror(ret));
+    *error_message = StrCat("open ", filename, " (within dir ",
+                            parent_dir_->name(), "): ", strerror(ret));
     return false;
   }
   return true;