diff --git a/src/system/libroot/posix/math/arch/x86/Jamfile b/src/system/libroot/posix/math/arch/x86/Jamfile
index 93ed03e951..5096fdc836 100644
--- a/src/system/libroot/posix/math/arch/x86/Jamfile
+++ b/src/system/libroot/posix/math/arch/x86/Jamfile
@@ -1,10 +1,12 @@
 SubDir OBOS_TOP src system libroot posix math arch x86 ;
 
 KernelMergeObject posix_math_arch_$(OBOS_ARCH).o :
-	<$(SOURCE_GRIST)>fabs.S
-	<$(SOURCE_GRIST)>frexp.c
-	<$(SOURCE_GRIST)>isinf.c
-	<$(SOURCE_GRIST)>ldexp.c
+	cos.S
+	fabs.S
+	frexp.c
+	isinf.c
+	ldexp.c
+	sin.S
 	:
 	-fPIC -DPIC
 	;
diff --git a/src/system/libroot/posix/math/arch/x86/cos.S b/src/system/libroot/posix/math/arch/x86/cos.S
new file mode 100644
index 0000000000..6681d35d83
--- /dev/null
+++ b/src/system/libroot/posix/math/arch/x86/cos.S
@@ -0,0 +1,30 @@
+/*
+ * Written by J.T. Conklin <jtc@netbsd.org>.
+ * Public domain.
+ */
+
+#define FUNCTION(x) .global x; .type x,@function; x
+#define FUNCTION_END(x)
+#define WEAK_ALIAS(original, alias) .weak original; original = alias
+
+FUNCTION(__cos):
+	fldl		4(%esp)
+	fcos
+	fnstsw		%ax
+	testl		$0x400,%eax
+	jnz			1f
+	ret
+	.align 4
+1:	fldpi
+	fadd		%st(0)
+	fxch		%st(1)
+2:	fprem1
+	fnstsw		%ax
+	testl		$0x400,%eax
+	jnz			2b
+	fstp		%st(1)
+	fcos
+	ret
+FUNCTION_END(__cos)
+
+WEAK_ALIAS(__cos, cos)
diff --git a/src/system/libroot/posix/math/arch/x86/sin.S b/src/system/libroot/posix/math/arch/x86/sin.S
new file mode 100644
index 0000000000..f9340245a6
--- /dev/null
+++ b/src/system/libroot/posix/math/arch/x86/sin.S
@@ -0,0 +1,30 @@
+/*
+ * Written by J.T. Conklin <jtc@netbsd.org>.
+ * Public domain.
+ */
+
+#define FUNCTION(x) .global x; .type x,@function; x
+#define FUNCTION_END(x)
+#define WEAK_ALIAS(original, alias) .weak original; original = alias
+
+FUNCTION(__sin):
+	fldl		4(%esp)
+	fsin
+	fnstsw		%ax
+	testl		$0x400,%eax
+	jnz			1f
+	ret
+	.align 4
+1:	fldpi
+	fadd		%st(0)
+	fxch		%st(1)
+2:	fprem1
+	fnstsw		%ax
+	testl		$0x400,%eax
+	jnz			2b
+	fstp		%st(1)
+	fsin
+	ret
+FUNCTION_END(__sin)
+
+WEAK_ALIAS(__sin, sin)