diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
index 7c713025b23f..0170602a1e4e 100644
--- a/arch/mips/include/asm/syscall.h
+++ b/arch/mips/include/asm/syscall.h
@@ -26,12 +26,34 @@
 #define __NR_syscall 4000
 #endif
 
+static inline bool mips_syscall_is_indirect(struct task_struct *task,
+					    struct pt_regs *regs)
+{
+	/* O32 ABI syscall() - Either 64-bit with O32 or 32-bit */
+	return (IS_ENABLED(CONFIG_32BIT) ||
+		test_tsk_thread_flag(task, TIF_32BIT_REGS)) &&
+		(regs->regs[2] == __NR_syscall);
+}
+
 static inline long syscall_get_nr(struct task_struct *task,
 				  struct pt_regs *regs)
 {
 	return current_thread_info()->syscall;
 }
 
+static inline void mips_syscall_update_nr(struct task_struct *task,
+					  struct pt_regs *regs)
+{
+	/*
+	 * v0 is the system call number, except for O32 ABI syscall(), where it
+	 * ends up in a0.
+	 */
+	if (mips_syscall_is_indirect(task, regs))
+		task_thread_info(task)->syscall = regs->regs[4];
+	else
+		task_thread_info(task)->syscall = regs->regs[2];
+}
+
 static inline unsigned long mips_get_syscall_arg(unsigned long *arg,
 	struct task_struct *task, struct pt_regs *regs, unsigned int n)
 {
@@ -98,10 +120,9 @@ static inline void syscall_get_arguments(struct task_struct *task,
 					 unsigned long *args)
 {
 	int ret;
-	/* O32 ABI syscall() - Either 64-bit with O32 or 32-bit */
-	if ((IS_ENABLED(CONFIG_32BIT) ||
-	    test_tsk_thread_flag(task, TIF_32BIT_REGS)) &&
-	    (regs->regs[2] == __NR_syscall))
+
+	/* O32 ABI syscall() */
+	if (mips_syscall_is_indirect(task, regs))
 		i++;
 
 	while (n--)
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 011993e0cce2..efbd8df8b665 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -144,6 +144,9 @@ int ptrace_setregs(struct task_struct *child, struct user_pt_regs __user *data)
 
 	/* badvaddr, status, and cause may not be written.  */
 
+	/* System call number may have been changed */
+	mips_syscall_update_nr(child, regs);
+
 	return 0;
 }
 
@@ -345,6 +348,9 @@ static int gpr32_set(struct task_struct *target,
 		}
 	}
 
+	/* System call number may have been changed */
+	mips_syscall_update_nr(target, regs);
+
 	return 0;
 }
 
@@ -405,6 +411,9 @@ static int gpr64_set(struct task_struct *target,
 		}
 	}
 
+	/* System call number may have been changed */
+	mips_syscall_update_nr(target, regs);
+
 	return 0;
 }
 
@@ -770,6 +779,12 @@ long arch_ptrace(struct task_struct *child, long request,
 		switch (addr) {
 		case 0 ... 31:
 			regs->regs[addr] = data;
+			/* System call number may have been changed */
+			if (addr == 2)
+				mips_syscall_update_nr(child, regs);
+			else if (addr == 4 &&
+				 mips_syscall_is_indirect(child, regs))
+				mips_syscall_update_nr(child, regs);
 			break;
 		case FPR_BASE ... FPR_BASE + 31: {
 			union fpureg *fregs = get_fpu_regs(child);
diff --git a/arch/mips/kernel/ptrace32.c b/arch/mips/kernel/ptrace32.c
index 40e212d6b26b..2b9260f92ccd 100644
--- a/arch/mips/kernel/ptrace32.c
+++ b/arch/mips/kernel/ptrace32.c
@@ -33,6 +33,7 @@
 #include <asm/pgtable.h>
 #include <asm/page.h>
 #include <asm/reg.h>
+#include <asm/syscall.h>
 #include <linux/uaccess.h>
 #include <asm/bootinfo.h>
 
@@ -195,6 +196,12 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 		switch (addr) {
 		case 0 ... 31:
 			regs->regs[addr] = data;
+			/* System call number may have been changed */
+			if (addr == 2)
+				mips_syscall_update_nr(child, regs);
+			else if (addr == 4 &&
+				 mips_syscall_is_indirect(child, regs))
+				mips_syscall_update_nr(child, regs);
 			break;
 		case FPR_BASE ... FPR_BASE + 31: {
 			union fpureg *fregs = get_fpu_regs(child);