diff --git a/src/tools/fs_shell/external_commands_beos.cpp b/src/tools/fs_shell/external_commands_beos.cpp
index 519bc13378..84b66e367a 100644
--- a/src/tools/fs_shell/external_commands_beos.cpp
+++ b/src/tools/fs_shell/external_commands_beos.cpp
@@ -11,8 +11,10 @@
 #include "external_commands.h"
 #include "fs_shell_command_beos.h"
 
+
 static port_id sReplyPort = -1;
 
+
 static port_id
 get_command_port()
 {
@@ -29,52 +31,54 @@ get_command_port()
 
 
 bool
-get_external_command(char *input, int len)
+FSShell::get_external_command(char *input, int len)
 {
 	// get/create the port
 	port_id port = get_command_port();
 	if (port < 0) {
-		fprintf(stderr, "Failed to create command port: %s\n", strerror(port));
+		fprintf(stderr, "Error: Failed to create command port: %s\n",
+			strerror(port));
 		return false;
 	}
 
 	while (true) {
 		// read a message
-		external_command_message message;
+		char _message[sizeof(external_command_message) + kMaxCommandLength];
+		external_command_message* message = (external_command_message*)_message;
 		ssize_t bytesRead;
 		do {
 			int32 code;
-			bytesRead = read_port(port, &code, &message, sizeof(message));
+			bytesRead = read_port(port, &code, message, sizeof(_message));
 		} while (bytesRead == B_INTERRUPTED);
 
 		if (bytesRead < 0) {
-			fprintf(stderr, "Reading from port failed: %s\n",
+			fprintf(stderr, "Error: Reading from port failed: %s\n",
 				strerror(bytesRead));
 			return false;
 		}
 
 		// get the len of the command
-		int commandLen = (char*)&message + bytesRead - message.command;
+		int commandLen = _message + bytesRead - message->command;
 		if (commandLen <= 1) {
-			fprintf(stderr, "No command given.\n");
+			fprintf(stderr, "Error: No command given.\n");
 			continue;
 		}
 		if (commandLen > len) {
-			fprintf(stderr, "Command too long. Ignored.\n");
+			fprintf(stderr, "Error: Command too long. Ignored.\n");
 			continue;
 		}
 
 		// copy the command
-		memcpy(input, message.command, commandLen);
+		memcpy(input, message->command, commandLen);
 		input[len - 1] = '\0';	// always NULL-terminate
-		sReplyPort = message.reply_port;
+		sReplyPort = message->reply_port;
 		return true;
 	}
 }
 
 
 void
-reply_to_external_command(int result)
+FSShell::reply_to_external_command(int result)
 {
 	if (sReplyPort >= 0) {
 		// prepare the message
@@ -89,15 +93,15 @@ reply_to_external_command(int result)
 		sReplyPort = -1;
 
 		if (error != B_OK) {
-			fprintf(stderr, "Failed to send command result to reply port: %s\n",
-				strerror(error));
+			fprintf(stderr, "Error: Failed to send command result to reply "
+				"port: %s\n", strerror(error));
 		}
 	}
 }
 
 
 void
-external_command_cleanup()
+FSShell::external_command_cleanup()
 {
 	// The port will be deleted automatically when the team exits.
 }
diff --git a/src/tools/fs_shell/fs_shell_command_beos.cpp b/src/tools/fs_shell/fs_shell_command_beos.cpp
index fe5b3f27dc..e72184f5a8 100644
--- a/src/tools/fs_shell/fs_shell_command_beos.cpp
+++ b/src/tools/fs_shell/fs_shell_command_beos.cpp
@@ -16,8 +16,15 @@
 bool
 send_external_command(const char *command, int *result)
 {
-	external_command_message message;
-	strncpy(message.command, command, sizeof(message.command));
+	int commandLen = strlen(command);
+	if (commandLen > kMaxCommandLength) {
+		fprintf(stderr, "Error: Command line too long.\n");
+		return false;
+	}
+
+	char _message[sizeof(external_command_message) + kMaxCommandLength];
+	external_command_message* message = (external_command_message*)_message;
+	strcpy(message->command, command);
 
 	// find the command port
 	port_id commandPort = find_port(kFSShellCommandPort);
@@ -33,12 +40,13 @@ send_external_command(const char *command, int *result)
 			strerror(replyPort));
 		return false;
 	}
-	message.reply_port = replyPort;
+	message->reply_port = replyPort;
 
 	// send the command message
 	status_t error;
 	do {
-		error = write_port(commandPort, 0, &message, sizeof(message));
+		error = write_port(commandPort, 0, message,
+			sizeof(external_command_message) + commandLen);
 	} while (error == B_INTERRUPTED);
 
 	if (error != B_OK) {
diff --git a/src/tools/fs_shell/fs_shell_command_beos.h b/src/tools/fs_shell/fs_shell_command_beos.h
index e90682c5a6..2b9ed6db54 100644
--- a/src/tools/fs_shell/fs_shell_command_beos.h
+++ b/src/tools/fs_shell/fs_shell_command_beos.h
@@ -5,12 +5,15 @@
 #ifndef FS_SHELL_COMMAND_BEOS_H
 #define FS_SHELL_COMMAND_BEOS_H
 
+#include <OS.h>
+
+
 static const char *kFSShellCommandPort = "fs shell command port";
+static const int kMaxCommandLength = 102400;
 
 struct external_command_message {
 	port_id		reply_port;
-	char		command[20480];
-// TODO: Increase command size and transmit only as much as necessary.
+	char		command[1];
 };
 
 struct external_command_reply {