diff --git a/source/Makefile b/source/Makefile
index 9e7fcdc..3a775c4 100644
--- a/source/Makefile
+++ b/source/Makefile
@@ -44,6 +44,7 @@ EXE_sources=\
   crc.c \
   cvar.c \
   mathlib.c \
+  math.S \
   md4.c \
   zone.c \
   pmove.c \
diff --git a/source/math.S b/source/math.S
new file mode 100644
index 0000000..465f914
--- /dev/null
+++ b/source/math.S
@@ -0,0 +1,331 @@
+//
+// math.s
+// x86 assembly-language math routines.
+
+#include "asm_i386.h"
+#include "quakeasm.h"
+
+
+#if id386
+
+	.data
+
+	.align	4
+Ljmptab:	.long	Lcase0, Lcase1, Lcase2, Lcase3
+			.long	Lcase4, Lcase5, Lcase6, Lcase7
+
+	.text
+
+
+#define EMINS	4+4
+#define EMAXS	4+8
+#define P		4+12
+
+	.align 2
+.globl C(BoxOnPlaneSide)
+C(BoxOnPlaneSide):
+	pushl	%ebx
+
+	movl	P(%esp),%edx
+	movl	EMINS(%esp),%ecx
+	xorl	%eax,%eax
+	movl	EMAXS(%esp),%ebx
+	movb	pl_signbits(%edx),%al
+	cmpb	$8,%al
+	jge		Lerror
+	flds	pl_normal(%edx)		// p->normal[0]
+	fld		%st(0)				// p->normal[0] | p->normal[0]
+	jmp		*Ljmptab(,%eax,4)
+
+
+//dist1= p->normal[0]*emaxs[0] + p->normal[1]*emaxs[1] + p->normal[2]*emaxs[2];
+//dist2= p->normal[0]*emins[0] + p->normal[1]*emins[1] + p->normal[2]*emins[2];
+Lcase0:
+	fmuls	(%ebx)				// p->normal[0]*emaxs[0] | p->normal[0]
+	flds	pl_normal+4(%edx)	// p->normal[1] | p->normal[0]*emaxs[0] |
+								//  p->normal[0]
+	fxch	%st(2)				// p->normal[0] | p->normal[0]*emaxs[0] |
+								//  p->normal[1]
+	fmuls	(%ecx)				// p->normal[0]*emins[0] |
+								//  p->normal[0]*emaxs[0] | p->normal[1]
+	fxch	%st(2)				// p->normal[1] | p->normal[0]*emaxs[0] |
+								//  p->normal[0]*emins[0]
+	fld		%st(0)				// p->normal[1] | p->normal[1] |
+								//  p->normal[0]*emaxs[0] |
+								//  p->normal[0]*emins[0]
+	fmuls	4(%ebx)				// p->normal[1]*emaxs[1] | p->normal[1] |
+								//  p->normal[0]*emaxs[0] |
+								//  p->normal[0]*emins[0]
+	flds	pl_normal+8(%edx)	// p->normal[2] | p->normal[1]*emaxs[1] |
+								//  p->normal[1] | p->normal[0]*emaxs[0] |
+								//  p->normal[0]*emins[0]
+	fxch	%st(2)				// p->normal[1] | p->normal[1]*emaxs[1] |
+								//  p->normal[2] | p->normal[0]*emaxs[0] |
+								//  p->normal[0]*emins[0]
+	fmuls	4(%ecx)				// p->normal[1]*emins[1] |
+								//  p->normal[1]*emaxs[1] |
+								//  p->normal[2] | p->normal[0]*emaxs[0] |
+								//  p->normal[0]*emins[0]
+	fxch	%st(2)				// p->normal[2] | p->normal[1]*emaxs[1] |
+								//  p->normal[1]*emins[1] |
+								//  p->normal[0]*emaxs[0] |
+								//  p->normal[0]*emins[0]
+	fld		%st(0)				// p->normal[2] | p->normal[2] |
+								//  p->normal[1]*emaxs[1] |
+								//  p->normal[1]*emins[1] |
+								//  p->normal[0]*emaxs[0] |
+								//  p->normal[0]*emins[0]
+	fmuls	8(%ebx)				// p->normal[2]*emaxs[2] |
+								//  p->normal[2] |
+								//  p->normal[1]*emaxs[1] |
+								//  p->normal[1]*emins[1] |
+								//  p->normal[0]*emaxs[0] |
+								//  p->normal[0]*emins[0]
+	fxch	%st(5)				// p->normal[0]*emins[0] |
+								//  p->normal[2] |
+								//  p->normal[1]*emaxs[1] |
+								//  p->normal[1]*emins[1] |
+								//  p->normal[0]*emaxs[0] |
+								//  p->normal[2]*emaxs[2]
+	faddp	%st(0),%st(3)		//p->normal[2] |
+								// p->normal[1]*emaxs[1] |
+								// p->normal[1]*emins[1]+p->normal[0]*emins[0]|
+								// p->normal[0]*emaxs[0] |
+								// p->normal[2]*emaxs[2]
+	fmuls	8(%ecx)				//p->normal[2]*emins[2] |
+								// p->normal[1]*emaxs[1] |
+								// p->normal[1]*emins[1]+p->normal[0]*emins[0]|
+								// p->normal[0]*emaxs[0] |
+								// p->normal[2]*emaxs[2]
+	fxch	%st(1)				//p->normal[1]*emaxs[1] |
+								// p->normal[2]*emins[2] |
+								// p->normal[1]*emins[1]+p->normal[0]*emins[0]|
+								// p->normal[0]*emaxs[0] |
+								// p->normal[2]*emaxs[2]
+	faddp	%st(0),%st(3)		//p->normal[2]*emins[2] |
+								// p->normal[1]*emins[1]+p->normal[0]*emins[0]|
+								// p->normal[0]*emaxs[0]+p->normal[1]*emaxs[1]|
+								// p->normal[2]*emaxs[2]
+	fxch	%st(3)				//p->normal[2]*emaxs[2] +
+								// p->normal[1]*emins[1]+p->normal[0]*emins[0]|
+								// p->normal[0]*emaxs[0]+p->normal[1]*emaxs[1]|
+								// p->normal[2]*emins[2]
+	faddp	%st(0),%st(2)		//p->normal[1]*emins[1]+p->normal[0]*emins[0]|
+								// dist1 | p->normal[2]*emins[2]
+
+	jmp		LSetSides
+
+//dist1= p->normal[0]*emins[0] + p->normal[1]*emaxs[1] + p->normal[2]*emaxs[2];
+//dist2= p->normal[0]*emaxs[0] + p->normal[1]*emins[1] + p->normal[2]*emins[2];
+Lcase1:
+	fmuls	(%ecx)				// emins[0]
+	flds	pl_normal+4(%edx)
+	fxch	%st(2)
+	fmuls	(%ebx)				// emaxs[0]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	4(%ebx)				// emaxs[1]
+	flds	pl_normal+8(%edx)
+	fxch	%st(2)
+	fmuls	4(%ecx)				// emins[1]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	8(%ebx)				// emaxs[2]
+	fxch	%st(5)
+	faddp	%st(0),%st(3)
+	fmuls	8(%ecx)				// emins[2]
+	fxch	%st(1)
+	faddp	%st(0),%st(3)
+	fxch	%st(3)
+	faddp	%st(0),%st(2)
+
+	jmp		LSetSides
+
+//dist1= p->normal[0]*emaxs[0] + p->normal[1]*emins[1] + p->normal[2]*emaxs[2];
+//dist2= p->normal[0]*emins[0] + p->normal[1]*emaxs[1] + p->normal[2]*emins[2];
+Lcase2:
+	fmuls	(%ebx)				// emaxs[0]
+	flds	pl_normal+4(%edx)
+	fxch	%st(2)
+	fmuls	(%ecx)				// emins[0]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	4(%ecx)				// emins[1]
+	flds	pl_normal+8(%edx)
+	fxch	%st(2)
+	fmuls	4(%ebx)				// emaxs[1]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	8(%ebx)				// emaxs[2]
+	fxch	%st(5)
+	faddp	%st(0),%st(3)
+	fmuls	8(%ecx)				// emins[2]
+	fxch	%st(1)
+	faddp	%st(0),%st(3)
+	fxch	%st(3)
+	faddp	%st(0),%st(2)
+
+	jmp		LSetSides
+
+//dist1= p->normal[0]*emins[0] + p->normal[1]*emins[1] + p->normal[2]*emaxs[2];
+//dist2= p->normal[0]*emaxs[0] + p->normal[1]*emaxs[1] + p->normal[2]*emins[2];
+Lcase3:
+	fmuls	(%ecx)				// emins[0]
+	flds	pl_normal+4(%edx)
+	fxch	%st(2)
+	fmuls	(%ebx)				// emaxs[0]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	4(%ecx)				// emins[1]
+	flds	pl_normal+8(%edx)
+	fxch	%st(2)
+	fmuls	4(%ebx)				// emaxs[1]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	8(%ebx)				// emaxs[2]
+	fxch	%st(5)
+	faddp	%st(0),%st(3)
+	fmuls	8(%ecx)				// emins[2]
+	fxch	%st(1)
+	faddp	%st(0),%st(3)
+	fxch	%st(3)
+	faddp	%st(0),%st(2)
+
+	jmp		LSetSides
+
+//dist1= p->normal[0]*emaxs[0] + p->normal[1]*emaxs[1] + p->normal[2]*emins[2];
+//dist2= p->normal[0]*emins[0] + p->normal[1]*emins[1] + p->normal[2]*emaxs[2];
+Lcase4:
+	fmuls	(%ebx)				// emaxs[0]
+	flds	pl_normal+4(%edx)
+	fxch	%st(2)
+	fmuls	(%ecx)				// emins[0]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	4(%ebx)				// emaxs[1]
+	flds	pl_normal+8(%edx)
+	fxch	%st(2)
+	fmuls	4(%ecx)				// emins[1]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	8(%ecx)				// emins[2]
+	fxch	%st(5)
+	faddp	%st(0),%st(3)
+	fmuls	8(%ebx)				// emaxs[2]
+	fxch	%st(1)
+	faddp	%st(0),%st(3)
+	fxch	%st(3)
+	faddp	%st(0),%st(2)
+
+	jmp		LSetSides
+
+//dist1= p->normal[0]*emins[0] + p->normal[1]*emaxs[1] + p->normal[2]*emins[2];
+//dist2= p->normal[0]*emaxs[0] + p->normal[1]*emins[1] + p->normal[2]*emaxs[2];
+Lcase5:
+	fmuls	(%ecx)				// emins[0]
+	flds	pl_normal+4(%edx)
+	fxch	%st(2)
+	fmuls	(%ebx)				// emaxs[0]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	4(%ebx)				// emaxs[1]
+	flds	pl_normal+8(%edx)
+	fxch	%st(2)
+	fmuls	4(%ecx)				// emins[1]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	8(%ecx)				// emins[2]
+	fxch	%st(5)
+	faddp	%st(0),%st(3)
+	fmuls	8(%ebx)				// emaxs[2]
+	fxch	%st(1)
+	faddp	%st(0),%st(3)
+	fxch	%st(3)
+	faddp	%st(0),%st(2)
+
+	jmp		LSetSides
+
+//dist1= p->normal[0]*emaxs[0] + p->normal[1]*emins[1] + p->normal[2]*emins[2];
+//dist2= p->normal[0]*emins[0] + p->normal[1]*emaxs[1] + p->normal[2]*emaxs[2];
+Lcase6:
+	fmuls	(%ebx)				// emaxs[0]
+	flds	pl_normal+4(%edx)
+	fxch	%st(2)
+	fmuls	(%ecx)				// emins[0]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	4(%ecx)				// emins[1]
+	flds	pl_normal+8(%edx)
+	fxch	%st(2)
+	fmuls	4(%ebx)				// emaxs[1]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	8(%ecx)				// emins[2]
+	fxch	%st(5)
+	faddp	%st(0),%st(3)
+	fmuls	8(%ebx)				// emaxs[2]
+	fxch	%st(1)
+	faddp	%st(0),%st(3)
+	fxch	%st(3)
+	faddp	%st(0),%st(2)
+
+	jmp		LSetSides
+
+//dist1= p->normal[0]*emins[0] + p->normal[1]*emins[1] + p->normal[2]*emins[2];
+//dist2= p->normal[0]*emaxs[0] + p->normal[1]*emaxs[1] + p->normal[2]*emaxs[2];
+Lcase7:
+	fmuls	(%ecx)				// emins[0]
+	flds	pl_normal+4(%edx)
+	fxch	%st(2)
+	fmuls	(%ebx)				// emaxs[0]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	4(%ecx)				// emins[1]
+	flds	pl_normal+8(%edx)
+	fxch	%st(2)
+	fmuls	4(%ebx)				// emaxs[1]
+	fxch	%st(2)
+	fld		%st(0)
+	fmuls	8(%ecx)				// emins[2]
+	fxch	%st(5)
+	faddp	%st(0),%st(3)
+	fmuls	8(%ebx)				// emaxs[2]
+	fxch	%st(1)
+	faddp	%st(0),%st(3)
+	fxch	%st(3)
+	faddp	%st(0),%st(2)
+
+LSetSides:
+
+//	sides = 0;
+//	if (dist1 >= p->dist)
+//		sides = 1;
+//	if (dist2 < p->dist)
+//		sides |= 2;
+
+	faddp	%st(0),%st(2)		// dist1 | dist2
+	fcomps	pl_dist(%edx)
+	xorl	%ecx,%ecx
+	fnstsw	%ax
+	fcomps	pl_dist(%edx)
+	andb	$1,%ah
+	xorb	$1,%ah
+	addb	%ah,%cl
+
+	fnstsw	%ax
+	andb	$1,%ah
+	addb	%ah,%ah
+	addb	%ah,%cl
+
+//	return sides;
+
+	popl	%ebx
+	movl	%ecx,%eax	// return status
+
+	ret
+
+
+Lerror:
+	call	C(BOPS_Error)
+
+#endif	// id386
diff --git a/source/mathlib.c b/source/mathlib.c
index 3da8c8d..630ae19 100644
--- a/source/mathlib.c
+++ b/source/mathlib.c
@@ -175,7 +175,7 @@ void BOPS_Error (void)
 	Sys_Error ("BoxOnPlaneSide:  Bad signbits");
 }
 
-//#if !id386
+#if !id386
 
 /*
 ==================
@@ -284,7 +284,7 @@ if (sides == 0)
 	return sides;
 }
 
-//#endif
+#endif
 
 
 void AngleVectors (vec3_t angles, vec3_t forward, vec3_t right, vec3_t up)