diff -urNp openmsx-20.0-orig/build/libraries.py openmsx-20.0/build/libraries.py
--- openmsx-20.0-orig/build/libraries.py	2025-04-03 17:53:57.000000000 +0300
+++ openmsx-20.0/build/libraries.py	2025-04-18 01:55:51.081067959 +0300
@@ -372,7 +372,7 @@ class TCL(Library):
 						if isdir(libpath):
 							yield libpath
 							for entry in listdir(libpath):
-								if entry.startswith('tcl8.'):
+								if entry.startswith('tcl9.'):
 									tclpath = libpath + '/' + entry
 									if isdir(tclpath):
 										yield tclpath
diff -urNp openmsx-20.0-orig/src/commands/Interpreter.cc openmsx-20.0/src/commands/Interpreter.cc
--- openmsx-20.0-orig/src/commands/Interpreter.cc	2025-04-03 17:53:57.000000000 +0300
+++ openmsx-20.0/src/commands/Interpreter.cc	2025-04-18 21:24:19.416413810 +0300
@@ -35,8 +35,7 @@ namespace {
 static std::vector<Trace> traces; // sorted on id
 static uintptr_t traceCount = 0;
 
-
-static int dummyClose(ClientData /*instanceData*/, Tcl_Interp* /*interp*/)
+static int dummyClose(void *foo, Tcl_Interp *bar, int baz)
 {
 	return 0;
 }
@@ -55,8 +54,8 @@ static int dummyGetHandle(ClientData /*i
 }
 Tcl_ChannelType Interpreter::channelType = {
 	"openMSX console",	 // Type name
-	nullptr,		 // Always non-blocking
-	dummyClose,		 // Close proc
+	TCL_CHANNEL_VERSION_5,
+	nullptr,		 // Close proc
 	dummyInput,		 // Input proc
 	Interpreter::outputProc, // Output proc
 	nullptr,		 // Seek proc
@@ -64,7 +63,7 @@ Tcl_ChannelType Interpreter::channelType
 	nullptr,		 // Get option proc
 	dummyWatch,		 // Watch for events on console
 	dummyGetHandle,		 // Get a handle from the device
-	nullptr,		 // Tcl_DriverClose2Proc
+	dummyClose,		 // Tcl_DriverClose2Proc
 	nullptr,		 // Tcl_DriverBlockModeProc
 	nullptr,		 // Tcl_DriverFlushProc
 	nullptr,		 // Tcl_DriverHandlerProc
diff -urNp openmsx-20.0-orig/src/commands/TclObject.cc openmsx-20.0/src/commands/TclObject.cc
--- openmsx-20.0-orig/src/commands/TclObject.cc	2025-04-03 17:53:57.000000000 +0300
+++ openmsx-20.0/src/commands/TclObject.cc	2025-04-18 00:43:30.929232289 +0300
@@ -140,14 +140,14 @@ std::optional<double> TclObject::getOpti
 
 zstring_view TclObject::getString() const
 {
-	int length;
+	long int length;
 	const char* buf = Tcl_GetStringFromObj(obj, &length);
 	return {buf, size_t(length)};
 }
 
 std::span<const uint8_t> TclObject::getBinary() const
 {
-	int length;
+	long int length;
 	const auto* buf = Tcl_GetByteArrayFromObj(obj, &length);
 	return {buf, size_t(length)};
 }
@@ -155,7 +155,7 @@ std::span<const uint8_t> TclObject::getB
 unsigned TclObject::getListLength(Interpreter& interp_) const
 {
 	auto* interp = interp_.interp;
-	int result;
+	long int result;
 	if (Tcl_ListObjLength(interp, obj, &result) != TCL_OK) {
 		throwException(interp);
 	}
@@ -163,7 +163,7 @@ unsigned TclObject::getListLength(Interp
 }
 unsigned TclObject::getListLengthUnchecked() const
 {
-	int result;
+	long int result;
 	if (Tcl_ListObjLength(nullptr, obj, &result) != TCL_OK) {
 		return 0; // error
 	}
diff -urNp openmsx-20.0-orig/src/commands/TclParser.cc openmsx-20.0/src/commands/TclParser.cc
--- openmsx-20.0-orig/src/commands/TclParser.cc	2025-04-03 17:53:57.000000000 +0300
+++ openmsx-20.0/src/commands/TclParser.cc	2025-04-18 00:41:55.219070475 +0300
@@ -98,7 +98,7 @@ void TclParser::parse(std::string parseS
 		bool allowComplete = ((offset + parseStr.size()) >= colors.size()) &&
 		                     (retryCount < 10);
 		Tcl_Obj* resObj = Tcl_GetObjResult(interp);
-		int resLen;
+		long int resLen;
 		const char* resStr = Tcl_GetStringFromObj(resObj, &resLen);
 		std::string_view error(resStr, resLen);