diff --git a/src/libc/cosf.src b/src/libc/cosf.src
deleted file mode 100644
index c654c601b..000000000
--- a/src/libc/cosf.src
+++ /dev/null
@@ -1,32 +0,0 @@
-	.assume	adl=1
-
-	.section	.text
-	.global	_cos
-	.type	_cos, @function
-	.global	_cosf
-	.type	_cosf, @function
-
-.ifdef PREFER_OS_LIBC
-
-	.set	_cosf, 0x02211C
-	.set	_cos, _cosf
-
-.else
-
-; float _f32_sinus(int quad, float arg)
-_cos:
-_cosf:
-	call	__frameset0
-	ld	e, (ix + 9) ; exponent
-	ld	hl, (ix + 6) ; mantissa
-	res	7, e	; fabsf(x)
-	push	de
-	push	hl
-	scf	; quad 1, N reset, C set
-	push	af
-	jp	_sinf.hijack
-
-	.extern	__frameset0
-	.extern	_sinf.hijack
-
-.endif
diff --git a/src/libc/sinf.c b/src/libc/sincosf.c
similarity index 100%
rename from src/libc/sinf.c
rename to src/libc/sincosf.c
diff --git a/src/libc/sincosf.src b/src/libc/sincosf.src
new file mode 100644
index 000000000..7abd29b48
--- /dev/null
+++ b/src/libc/sincosf.src
@@ -0,0 +1,93 @@
+	.assume	adl=1
+
+	.section	.text
+
+	.global	_sinf
+	.type	_sinf, @function
+	.global	_sin
+	.type	_sin, @function
+
+.ifdef PREFER_OS_LIBC
+
+	.set	_sinf, 0x022118
+	.set	_sin, _sinf
+
+.else
+
+; float _f32_sinus(int quad, float arg)
+_sin:
+_sinf:
+	ld	hl, 6
+	add	hl, sp
+	ld	e, (hl)		; exponent
+	dec	hl
+	dec	hl
+	dec	hl
+	ld	hl, (hl)	; mantissa
+	ld	a, e
+	add	a, a		; clear signbit
+	sub	a, 117		; |x| < 2^-10 or 0x3affffff
+	ret	c		; sin(x) = x for small arguments
+	ld	a, e
+	res	7, e		; x = fabsf(x)
+	push	de		; exponent
+	push	hl		; mantissa
+	rlca
+	add	a, a
+	ld	e, a
+	push	de
+	.local	_sinf.hijack
+_sinf.hijack:
+	call	__f32_sinus
+	pop	bc
+	pop	bc
+	pop	bc
+	; you can ret here if clamping is not needed
+	; clamp the result to [-1.0, +1.0]
+	ld	a, e
+	add	a, a
+	sub	a, 126
+	ret	nz		; |y| < 0.5f
+	push	hl
+	add	hl, hl
+	pop	hl
+	ret	nc		; |y| < 1.0f
+	ld	l, h		; zero out the lower 8 bits of the mantissa
+	ret
+
+	.extern	__f32_sinus
+
+.endif
+
+	.section	.text
+
+	.global	_cosf
+	.type	_cosf, @function
+	.global	_cos
+	.type	_cos, @function
+
+.ifdef PREFER_OS_LIBC
+
+	.set	_cosf, 0x02211C
+	.set	_cos, _cosf
+
+.else
+
+; float _f32_sinus(int quad, float arg)
+_cos:
+_cosf:
+	ld	hl, 6
+	add	hl, sp
+	ld	e, (hl)		; exponent
+	dec	hl
+	dec	hl
+	dec	hl
+	ld	hl, (hl)	; mantissa
+	res	7, e		; fabsf(x)
+	push	de
+	push	hl
+	scf			; quad 1, N reset, C set
+	push	af
+	jr	_sinf.hijack
+
+.endif
diff --git a/src/libc/sinf.src b/src/libc/sinf.src
deleted file mode 100644
index 45d7c09d5..000000000
--- a/src/libc/sinf.src
+++ /dev/null
@@ -1,58 +0,0 @@
-	.assume	adl=1
-
-	.section	.text
-
-	.global	_sinf
-	.type	_sinf, @function
-	.global	_sin
-	.type	_sin, @function
-
-.ifdef PREFER_OS_LIBC
-
-	.set	_sinf, 0x022118
-	.set	_sin, _sinf
-
-.else
-
-	.global	_sinf.hijack
-
-; float _f32_sinus(int quad, float arg)
-_sin:
-_sinf:
-	call	__frameset0
-	ld	e, (ix + 9) ; exponent
-	ld	hl, (ix + 6) ; mantissa
-	ld	a, e
-	add	a, a	; clear signbit
-	sub	a, 117	; |x| < 2^-10 or 0x3affffff
-	jr	c, _sinf.small_arg
-	ld	a, e
-	res	7, e	; x = fabsf(x)
-	push	de	; exponent
-	push	hl	; mantissa
-	rlca
-	add	a, a
-	ld	e, a
-	push	de
-_sinf.hijack:
-	call	__f32_sinus
-_sinf.small_arg:
-	ld	sp, ix
-	pop	ix
-	; you can ret here if clamping is not needed
-	; clamp the result to [-1.0, +1.0]
-	ld	a, e
-	add	a, a
-	sub	a, 126
-	ret	nz	; |y| < 0.5f
-	push	hl
-	add	hl, hl
-	pop	hl
-	ret	nc	; |y| < 1.0f
-	ld	l, h	; zero out the lower 8 bits of the mantissa
-	ret
-
-	.extern	__frameset0
-	.extern	__f32_sinus
-
-.endif