diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h
index aece7d8951535a363e685ef221b48023304a8967..68609f42193485d015409b37af7ff91a53fc625d 100644
--- a/tools/include/nolibc/arch-x86_64.h
+++ b/tools/include/nolibc/arch-x86_64.h
@@ -179,6 +179,9 @@ void *memmove(void *dst, const void *src, size_t len);
 #define NOLIBC_ARCH_HAS_MEMCPY
 void *memcpy(void *dst, const void *src, size_t len);
 
+#define NOLIBC_ARCH_HAS_MEMSET
+void *memset(void *dst, int c, size_t len);
+
 __asm__ (
 ".section .text.nolibc_memmove_memcpy\n"
 ".weak memmove\n"
@@ -200,6 +203,16 @@ __asm__ (
 	"rep movsb\n\t"
 	"cld\n\t"
 	"retq\n"
+
+".section .text.nolibc_memset\n"
+".weak memset\n"
+"memset:\n"
+	"xchgl %eax, %esi\n\t"
+	"movq  %rdx, %rcx\n\t"
+	"pushq %rdi\n\t"
+	"rep stosb\n\t"
+	"popq  %rax\n\t"
+	"retq\n"
 );
 
 #endif /* _NOLIBC_ARCH_X86_64_H */
diff --git a/tools/include/nolibc/string.h b/tools/include/nolibc/string.h
index 6eca267ec6fa717712a2fd0d9e930f95a293da52..1bad6121ef8c4ab536569e5ba92f501c095fe341 100644
--- a/tools/include/nolibc/string.h
+++ b/tools/include/nolibc/string.h
@@ -84,6 +84,7 @@ void *memcpy(void *dst, const void *src, size_t len)
 }
 #endif /* #ifndef NOLIBC_ARCH_HAS_MEMCPY */
 
+#ifndef NOLIBC_ARCH_HAS_MEMSET
 /* might be ignored by the compiler without -ffreestanding, then found as
  * missing.
  */
@@ -99,6 +100,7 @@ void *memset(void *dst, int b, size_t len)
 	}
 	return dst;
 }
+#endif /* #ifndef NOLIBC_ARCH_HAS_MEMSET */
 
 static __attribute__((unused))
 char *strchr(const char *s, int c)