diff --git a/lib/libc/riscv/gen/fabs.S b/lib/libc/riscv/gen/fabs.S
index 44249252e9c1..09042af3b4c0 100644
--- a/lib/libc/riscv/gen/fabs.S
+++ b/lib/libc/riscv/gen/fabs.S
@@ -1,43 +1,50 @@
 /*-
  * Copyright (c) 2015-2017 Ruslan Bukin <br@bsdpad.com>
+ * Copyright (c) 2021 Alex Richardson <arichardson@FreeBSD.org>
  * All rights reserved.
  *
  * Portions of this software were developed by SRI International and the
  * University of Cambridge Computer Laboratory under DARPA/AFRL contract
  * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
  *
  * Portions of this software were developed by the University of Cambridge
  * Computer Laboratory as part of the CTSRD Project, with support from the
  * UK Higher Education Innovation Fund (HEIF).
  *
+ * This work was supported by Innovate UK project 105694, "Digital Security
+ * by Design (DSbD) Technology Platform Prototype".
+ *
  * 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>
 __FBSDID("$FreeBSD$");
 
-#ifdef __riscv_float_abi_double
 ENTRY(fabs)
+#ifdef __riscv_float_abi_double
 	fabs.d	fa0, fa0
+#else
+	slli a0,a0,1
+	srli a0,a0,1
+#endif
 	ret
 END(fabs)
-#endif