diff --git a/src/Makefile.am b/src/Makefile.am
index 651b2aa..d056d0d 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -24,6 +24,7 @@ ttyvaders_SOURCES = \
 	common.h \
 	explosions.c \
 	main.c \
+	math.c \
 	starfield.c \
 	weapons.c \
 	collide.c \
diff --git a/src/common.h b/src/common.h
index 5de390e..5b08181 100644
--- a/src/common.h
+++ b/src/common.h
@@ -3,7 +3,7 @@
  *   Copyright (c) 2002 Sam Hocevar <sam@zoy.org>
  *                 All Rights Reserved
  *
- *   $Id: common.h,v 1.8 2002/12/22 22:17:41 sam Exp $
+ *   $Id: common.h,v 1.9 2002/12/22 22:36:42 sam Exp $
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -185,3 +185,5 @@ void update_explosions( game *g, explosions *ex );
 
 void ceo_alert( void );
 
+int r00t( int a );
+
diff --git a/src/math.c b/src/math.c
new file mode 100644
index 0000000..24bb71d
--- /dev/null
+++ b/src/math.c
@@ -0,0 +1,37 @@
+/*
+ *   ttyvaders     Textmode shoot'em up
+ *   Copyright (c) 2002 Sam Hocevar <sam@zoy.org>
+ *                 All Rights Reserved
+ *
+ *   $Id: math.c,v 1.1 2002/12/22 22:36:42 sam Exp $
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "common.h"
+
+int r00t( int a )
+{
+    int x = a > 100000 ? 1000 : a > 1000 ? 100 : a > 10 ? 10 : 1;
+
+    /* Newton's method. Three iterations are more than enough. */
+    x = (x * x + a) / x / 2;
+    x = (x * x + a) / x / 2;
+    x = (x * x + a) / x / 2;
+    x = (x * x + a) / x / 2;
+
+    return x;
+}
+
diff --git a/src/weapons.c b/src/weapons.c
index fbc8c2a..6d512fd 100644
--- a/src/weapons.c
+++ b/src/weapons.c
@@ -3,7 +3,7 @@
  *   Copyright (c) 2002 Sam Hocevar <sam@zoy.org>
  *                 All Rights Reserved
  *
- *   $Id: weapons.c,v 1.8 2002/12/22 22:17:41 sam Exp $
+ *   $Id: weapons.c,v 1.9 2002/12/22 22:36:42 sam Exp $
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -21,7 +21,6 @@
  */
 
 #include <stdlib.h>
-#include <math.h>
 
 #include "common.h"
 
@@ -172,9 +171,9 @@ void update_weapons( game *g, weapons *wp )
 
                 /* Normalize and update speed */
                 wp->vx[i] = (7 * wp->vx[i]
-                              + (dx * 48) / sqrt(dx*dx+dy*dy) ) / 8;
+                              + (dx * 48) / r00t(dx*dx+dy*dy) ) / 8;
                 wp->vy[i] = (7 * wp->vy[i]
-                              + (dy * 24) / sqrt(dx*dx+dy*dy) ) / 8;
+                              + (dy * 24) / r00t(dx*dx+dy*dy) ) / 8;
 
                 break;
             case WEAPON_FRAGBOMB: