diff --git a/lib/libc/riscv/string/Makefile.inc b/lib/libc/riscv/string/Makefile.inc
new file mode 100644
--- /dev/null
+++ b/lib/libc/riscv/string/Makefile.inc
@@ -0,0 +1,2 @@
+MDSRCS+= \
+	memset.S
diff --git a/lib/libc/riscv/string/memset.S b/lib/libc/riscv/string/memset.S
new file mode 100644
--- /dev/null
+++ b/lib/libc/riscv/string/memset.S
@@ -0,0 +1,116 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Strahinja Stanisic <strajabot@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <machine/asm.h>
+
+/*
+ * register a0 - void* s
+ * register a1 - int c
+ * register a2 - size_t n
+ */
+ENTRY(memset)
+	andi a1, a1, 0xFF
+
+	slti t1, a2, 8
+	mv t0, a0
+	bnez t1, .Lend
+
+	li t1, 0x0101010101010101
+	mul a1, a1, t1
+
+	andi t1, a0, 0b111
+	andi t0, a0, ~0b111
+
+	beqz t1, .Lloop_store_64
+
+	la t2, .Lduff_start
+	slli t3, t1, 2
+	add t2, t2, t3
+	jr -4(t2)
+.Lduff_start:
+	sb a1, 1(t0)
+	sb a1, 2(t0)
+	sb a1, 3(t0)
+	sb a1, 4(t0)
+	sb a1, 5(t0)
+	sb a1, 6(t0)
+	sb a1, 7(t0)
+
+	/* a3 = a3 -(8-a) <=> a3 = a3 + (a-8) */
+	addi t1, t1, -8
+	add a2, a2, t1
+	addi t0, t0, 8
+
+.Lloop_store_64:
+	slti t1, a2, 64
+	bnez t1, .Lstore_rest
+	sd a1, 0(t0)
+	sd a1, 8(t0)
+	sd a1, 16(t0)
+	sd a1, 24(t0)
+	sd a1, 32(t0)
+	sd a1, 40(t0)
+	sd a1, 48(t0)
+	sd a1, 56(t0)
+	addi a2, a2, -64
+	addi t0, t0, 64
+	j .Lloop_store_64
+
+.Lstore_rest:
+	la t2, .Lduff_rest
+	andi t3, a2, ~0b111
+	srli t4, t3, 1
+	sub t2, t2, t4
+	jr t2
+	sd a1, 56(t0)
+	sd a1, 48(t0)
+	sd a1, 40(t0)
+	sd a1, 32(t0)
+	sd a1, 24(t0)
+	sd a1, 16(t0)
+	sd a1, 8(t0)
+	sd a1, 0(t0)
+.Lduff_rest:
+	add t0, t0, t3
+	sub a2, a2, t3
+
+.Lend:
+	slli a2, a2, 2
+	la t2, .Lduff_end
+	sub t2, t2, a2
+	jr t2
+	sb a1, 6(t0)
+	sb a1, 5(t0)
+	sb a1, 4(t0)
+	sb a1, 3(t0)
+	sb a1, 2(t0)
+	sb a1, 1(t0)
+	sb a1, (t0)
+.Lduff_end:
+	ret
+END(memset)
+
diff --git a/share/man/man7/simd.7 b/share/man/man7/simd.7
--- a/share/man/man7/simd.7
+++ b/share/man/man7/simd.7
@@ -50,7 +50,7 @@
 .Pp
 Enhanced functions are present for the following architectures:
 .Bl -column FUNCTION_________ aarch64_ arm_ amd64_ i386_ ppc64_ -offset indent
-.It Em FUNCTION          Ta Em AARCH64 Ta Em ARM Ta Em AMD64  Ta Em I386 Ta Em PPC64
+.It Em FUNCTION          Ta Em AARCH64 Ta Em ARM Ta Em AMD64  Ta Em I386 Ta Em PPC64 Ta Em RISC-V
 .It    bcmp              Ta            Ta        Ta    S1     Ta    S
 .It    bcopy             Ta            Ta    S   Ta    S      Ta    S    Ta    SV
 .It    bzero             Ta            Ta    S   Ta    S      Ta    S
@@ -64,7 +64,7 @@
 .It    memcpy            Ta    S       Ta    S   Ta    S      Ta    S    Ta    SV
 .It    memmove           Ta    S       Ta    S   Ta    S      Ta    S    Ta    SV
 .It    memrchr           Ta    A       Ta        Ta    S1
-.It    memset            Ta    A       Ta    S   Ta    S      Ta    S
+.It    memset            Ta    A       Ta    S   Ta    S      Ta    S    Ta          Ta    S
 .It    rindex            Ta    A       Ta        Ta    S1     Ta    S
 .It    stpcpy            Ta    A       Ta        Ta    S1
 .It    stpncpy           Ta            Ta        Ta    S1