diff --git a/libc/startup/linux/riscv/start.cpp b/libc/startup/linux/riscv/start.cpp
--- a/libc/startup/linux/riscv/start.cpp
+++ b/libc/startup/linux/riscv/start.cpp
@@ -80,7 +80,11 @@
 }
 
 static void set_thread_ptr(uintptr_t val) {
+#ifdef LIBC_TARGET_ARCH_IS_RISCV32
+  LIBC_INLINE_ASM("lw tp, %0\n\t" : : "m"(val));
+#else // LIBC_TARGET_ARCH_IS_RISCV64
   LIBC_INLINE_ASM("ld tp, %0\n\t" : : "m"(val));
+#endif
 }
 
 using InitCallback = void(int, char **, char **);