diff --git a/lib/std/Thread.zig b/lib/std/Thread.zig
index a6ce01442d..d7e4f0f019 100644
--- a/lib/std/Thread.zig
+++ b/lib/std/Thread.zig
@@ -1264,7 +1264,7 @@ const LinuxThreadImpl = struct {
                     \\ ori r12, r0, 91 # SYS_munmap
                     \\ brki r14, 0x8
                     \\ ori r12, r0, 1 # SYS_exit
-                    \\ or r5, r0, r0
+                    \\ ori r5, r0, 0
                     \\ brki r14, 0x8
                     :
                     : [ptr] "{r5}" (@intFromPtr(self.mapped.ptr)),
diff --git a/lib/std/start.zig b/lib/std/start.zig
index 5ff0ce9dfe..6a20adf011 100644
--- a/lib/std/start.zig
+++ b/lib/std/start.zig
@@ -170,7 +170,7 @@ fn _start() callconv(.naked) noreturn {
             .loongarch32, .loongarch64 => ".cfi_undefined 1",
             .m68k => ".cfi_undefined %%pc",
             .m88k => ".cfi_undefined %%r1",
-            .microblaze, .microblazeel => ".cfi_undefined r15",
+            .microblaze, .microblazeel => "", // No CFI support.
             .mips, .mipsel, .mips64, .mips64el => ".cfi_undefined $ra",
             .or1k => ".cfi_undefined r9",
             .powerpc, .powerpcle, .powerpc64, .powerpc64le => ".cfi_undefined lr",
@@ -345,11 +345,11 @@ fn _start() callconv(.naked) noreturn {
             ,
             .microblaze, .microblazeel =>
             // r1 = SP, r15 = LR, r19 = FP, r20 = GP
-            \\ ori r15, r0, r0
-            \\ ori r19, r0, r0
+            \\ ori r15, r0, 0
+            \\ ori r19, r0, 0
             \\ mfs r20, rpc
-            \\ addik r20, r20, _GLOBAL_OFFSET_TABLE_ + 8
-            \\ ori r5, r1, r0
+            \\ addi r20, r20, _GLOBAL_OFFSET_TABLE_ + 8
+            \\ ori r5, r1, 0
             \\ andi r1, r1, -4
             \\ brlid r15, %[posixCallMainAndExit]
             ,