diff --git a/partition.cpp b/partition.cpp
index b421598..c278fa9 100644
--- a/partition.cpp
+++ b/partition.cpp
@@ -2275,17 +2275,45 @@
 			NeedPreserveFooter = false;
 		}
 
-		unsigned long long dev_sz = TWFunc::IOCTL_Get_Block_Size(Actual_Block_Device.c_str());
-		if (!dev_sz)
-			return false;
-
-		if (NeedPreserveFooter)
-			Length < 0 ? dev_sz += Length : dev_sz -= CRYPT_FOOTER_OFFSET;
-
 		gui_msg(Msg("formatting_using=Formatting {1} using {2}...")(Display_Name)("mkfs.f2fs"));
-		command = "mkfs.f2fs -d1 -f -O encrypt -O quota -O verity -w 4096 " + Actual_Block_Device + " " + to_string(dev_sz / 4096);
-		if (TWFunc::Path_Exists("/sbin/sload.f2fs")) {
-			command += " && sload.f2fs -t /data " + Actual_Block_Device;
+		// First determine if we have the old mkfs.f2fs that uses "-r reserved_bytes"
+		// or the new mkfs.f2fs that expects the number of sectors as the optional last argument
+		// Note: some 7.1 trees have the old and some have the new.
+		command = "mkfs.f2fs | grep \"reserved\" > /tmp/f2fsversiontest";
+		TWFunc::Exec_Cmd(command, false); // no help argument so printing usage exits with an error code
+		if (!TWFunc::Path_Exists("/tmp/f2fsversiontest")) {
+			LOGINFO("Error determining mkfs.f2fs version\n");
+			return false;
+		}
+		if (TWFunc::Get_File_Size("/tmp/f2fsversiontest") <= 0) {
+			LOGINFO("Using newer mkfs.f2fs\n");
+			unsigned long long dev_sz = TWFunc::IOCTL_Get_Block_Size(Actual_Block_Device.c_str());
+			if (!dev_sz)
+				return false;
+
+			if (NeedPreserveFooter)
+				Length < 0 ? dev_sz += Length : dev_sz -= CRYPT_FOOTER_OFFSET;
+
+			char dev_sz_str[48];
+			sprintf(dev_sz_str, "%llu", (dev_sz / 4096));
+			command = "mkfs.f2fs -d1 -f -O encrypt -O quota -O verity -w 4096 " + Actual_Block_Device + " " + dev_sz_str;
+			if (TWFunc::Path_Exists("/sbin/sload.f2fs")) {
+				command += " && sload.f2fs -t /data " + Actual_Block_Device;
+			}
+		} else {
+			LOGINFO("Using older mkfs.f2fs\n");
+			command = "mkfs.f2fs -t 0";
+			if (NeedPreserveFooter) {
+				// Only use length if we're not decrypted
+				char len[32];
+				int mod_length = Length;
+				if (Length < 0)
+					mod_length *= -1;
+				sprintf(len, "%i", mod_length);
+				command += " -r ";
+				command += len;
+			}
+			command += " " + Actual_Block_Device;
 		}
 		LOGINFO("mkfs.f2fs command: %s\n", command.c_str());
 		if (TWFunc::Exec_Cmd(command) == 0) {
diff --git a/twrp-functions.cpp b/twrp-functions.cpp
index ff34828..84451b3 100755
--- a/twrp-functions.cpp
+++ b/twrp-functions.cpp
@@ -77,7 +77,7 @@
 	return ret;
 }
 
-int TWFunc::Exec_Cmd(const string& cmd) {
+int TWFunc::Exec_Cmd(const string& cmd, bool Show_Errors) {
 	pid_t pid;
 	int status;
 	switch(pid = fork())
@@ -91,7 +91,7 @@
 			break;
 		default:
 		{
-			if (TWFunc::Wait_For_Child(pid, &status, cmd) != 0)
+			if (TWFunc::Wait_For_Child(pid, &status, cmd, Show_Errors) != 0)
 				return -1;
 			else
 				return 0;
@@ -121,18 +121,20 @@
 		return Path;
 }
 
-int TWFunc::Wait_For_Child(pid_t pid, int *status, string Child_Name) {
+int TWFunc::Wait_For_Child(pid_t pid, int *status, string Child_Name, bool Show_Errors) {
 	pid_t rc_pid;
 
 	rc_pid = waitpid(pid, status, 0);
 	if (rc_pid > 0) {
 		if (WIFSIGNALED(*status)) {
-			gui_msg(Msg(msg::kError, "pid_signal={1} process ended with signal: {2}")(Child_Name)(WTERMSIG(*status))); // Seg fault or some other non-graceful termination
+			if (Show_Errors)
+				gui_msg(Msg(msg::kError, "pid_signal={1} process ended with signal: {2}")(Child_Name)(WTERMSIG(*status))); // Seg fault or some other non-graceful termination
 			return -1;
 		} else if (WEXITSTATUS(*status) == 0) {
 			LOGINFO("%s process ended with RC=%d\n", Child_Name.c_str(), WEXITSTATUS(*status)); // Success
 		} else {
-			gui_msg(Msg(msg::kError, "pid_error={1} process ended with ERROR: {2}")(Child_Name)(WEXITSTATUS(*status))); // Graceful exit, but there was an error
+			if (Show_Errors)
+				gui_msg(Msg(msg::kError, "pid_error={1} process ended with ERROR: {2}")(Child_Name)(WEXITSTATUS(*status))); // Graceful exit, but there was an error
 			return -1;
 		}
 	} else { // no PID returned
diff --git a/twrp-functions.hpp b/twrp-functions.hpp
index efaa460..669a9e9 100755
--- a/twrp-functions.hpp
+++ b/twrp-functions.hpp
@@ -56,8 +56,8 @@
 	static string Get_Filename(const string& Path);                             // Trims the path off of a filename
 
 	static int Exec_Cmd(const string& cmd, string &result);                     //execute a command and return the result as a string by reference
-	static int Exec_Cmd(const string& cmd);                                     //execute a command
-	static int Wait_For_Child(pid_t pid, int *status, string Child_Name);       // Waits for pid to exit and checks exit status
+	static int Exec_Cmd(const string& cmd, bool Show_Errors = true);                   //execute a command, displays an error to the GUI if Show_Errors is true, Show_Errors is true by default
+	static int Wait_For_Child(pid_t pid, int *status, string Child_Name, bool Show_Errors = true); // Waits for pid to exit and checks exit status, displays an error to the GUI if Show_Errors is true which is the default
 	static int Wait_For_Child_Timeout(pid_t pid, int *status, const string& Child_Name, int timeout); // Waits for a pid to exit until the timeout is hit. If timeout is hit, kill the chilld.
 	static bool Path_Exists(string Path);                                       // Returns true if the path exists
 	static Archive_Type Get_File_Type(string fn);                               // Determines file type, 0 for unknown, 1 for gzip, 2 for OAES encrypted