diff --git a/src/Files/Files.cpp b/src/Files/Files.cpp
index 1509cae..3447c42 100644
--- a/src/Files/Files.cpp
+++ b/src/Files/Files.cpp
@@ -151,6 +151,13 @@ OSErr FSpOpenRF(const FSSpec* spec, char permission, short* refNum)
 	return OpenFork(spec, ForkType::ResourceFork, permission, refNum);
 }
 
+OSErr FSOpen(const char* cName, short vRefNum, short* refNum)
+{
+	FSSpec spec;
+	FSMakeFSSpec(vRefNum, 0, cName, &spec);
+	return FSpOpenDF(&spec, fsRdPerm, refNum);
+}
+
 OSErr FindFolder(short vRefNum, OSType folderType, Boolean createFolder, short* foundVRefNum, long* foundDirID)
 {
 	if (vRefNum != kOnSystemDisk)
@@ -283,6 +290,15 @@ OSErr ResolveAlias(const FSSpec* spec, AliasHandle alias, FSSpec* target, Boolea
 	return FSMakeFSSpec(spec->vRefNum, spec->parID, targetFilename.c_str(), target);
 }
 
+OSErr GetVol(char* outVolNameC, short* vRefNum)
+{
+	if (vRefNum)
+		*vRefNum = 0;
+	if (outVolNameC)
+		*outVolNameC = '\0';
+	return nsvErr;
+}
+
 OSErr FSRead(short refNum, long* count, Ptr buffPtr)
 {
 	if (*count < 0) return paramErr;
diff --git a/src/Files/HostVolume.cpp b/src/Files/HostVolume.cpp
index 69048cf..c0da0b4 100644
--- a/src/Files/HostVolume.cpp
+++ b/src/Files/HostVolume.cpp
@@ -70,7 +70,7 @@ long HostVolume::GetDirectoryID(const fs::path& dirPath)
 
 fs::path HostVolume::ToPath(long parID, const std::string& name)
 {
-	fs::path path = directories[parID] / AsU8(name);
+	fs::path path = directories.at(parID) / AsU8(name);
 	return path.lexically_normal();
 }
 
@@ -213,7 +213,7 @@ OSErr HostVolume::FSMakeFSSpec(long dirID, const std::string& fileName, FSSpec*
 		throw std::runtime_error("HostVolume::FSMakeFSSpec: directory ID not registered.");
 	}
 
-	auto path = directories[dirID];
+	auto path = directories.at(dirID);
 	auto suffix = fileName;
 
 	// Case-insensitive sanitization
diff --git a/src/Files/Resources.cpp b/src/Files/Resources.cpp
index 872eac3..9dcd8e6 100644
--- a/src/Files/Resources.cpp
+++ b/src/Files/Resources.cpp
@@ -207,6 +207,13 @@ short FSpOpenResFile(const FSSpec* spec, char permission)
 	return slot;
 }
 
+short OpenResFile(const char* cName)
+{
+	FSSpec spec;
+	FSMakeFSSpec(0, 0, cName, &spec);
+	return FSpOpenResFile(&spec, fsRdPerm);
+}
+
 void UseResFile(short refNum)
 {
 	// See MoreMacintoshToolbox:1-69
@@ -315,6 +322,11 @@ void AddResource(Handle theData, ResType theType, short theID, const char* name)
 	TODO();
 }
 
+void ChangedResource(Handle theResource)
+{
+	TODO();
+}
+
 void WriteResource(Handle theResource)
 {
 	TODO();
diff --git a/src/Pomme.h b/src/Pomme.h
index c5d8935..dc0741b 100644
--- a/src/Pomme.h
+++ b/src/Pomme.h
@@ -29,7 +29,7 @@ extern "C"
 #endif
 
 //-----------------------------------------------------------------------------
-// FSSpec
+// File/volume management
 
 OSErr FSMakeFSSpec(short vRefNum, long dirID, const char* cstrFileName, FSSpec* spec);
 
@@ -41,6 +41,16 @@ OSErr FSpOpenDF(const FSSpec* spec, char permission, short* refNum);
 // Open a file's resource fork
 OSErr FSpOpenRF(const FSSpec* spec, char permission, short* refNum);
 
+// Open a file's data fork with fsRdPerm (TODO: it should be fsCurPerm, but we don't support fsCurPerm yet)
+// in directory 0 of the given volume. It is legal to pass in a colon-separated hierarchical path in cName.
+// (Note: this is an ancient function that predates HFS - IM vol II, 1985)
+OSErr FSOpen(const char* cName, short vRefNum, short* refNum);
+
+// Open a file's resource fork with fsRdPerm (TODO: it should be fsCurPerm, but we don't support fsCurPerm yet)
+// in directory 0 of the application's volume. It is legal to pass in a colon-separated hierarchical path in cName.
+// (Note: this is an ancient function that predates HFS - IM vol II, 1985)
+short OpenResFile(const char* cName);
+
 OSErr FSpCreate(const FSSpec* spec, OSType creator, OSType fileType, ScriptCode scriptTag);
 
 OSErr FSpDelete(const FSSpec* spec);
@@ -51,6 +61,8 @@ OSErr FindFolder(short vRefNum, OSType folderType, Boolean createFolder, short*
 
 OSErr DirCreate(short vRefNum, long parentDirID, const char* cstrDirectoryName, long* createdDirID);
 
+OSErr GetVol(char* outVolNameC, short* vRefNum);
+
 //-----------------------------------------------------------------------------
 // File I/O
 
@@ -93,6 +105,8 @@ void RemoveResource(Handle theResource);
 
 void AddResource(Handle theData, ResType theType, short theID, const char* name);
 
+void ChangedResource(Handle theResource);
+
 void WriteResource(Handle theResource);
 
 void DetachResource(Handle theResource);