diff --git a/spearmint/kernels/kernel_utils.py b/spearmint/kernels/kernel_utils.py
index c84248d..956d936 100755
--- a/spearmint/kernels/kernel_utils.py
+++ b/spearmint/kernels/kernel_utils.py
@@ -210,33 +210,7 @@ def dist2(ls, x1, x2=None):
 def grad_dist2(ls, x1, x2=None):
     if x2 is None:
         x2 = x1
-        
-    # Rescale.
-    x1 = x1 / ls
-    x2 = x2 / ls
-    
-    N = x1.shape[0]
-    M = x2.shape[0]
-    D = x1.shape[1]
-    gX = np.zeros((x1.shape[0],x2.shape[0],x1.shape[1]))
-
-    code = \
-    """
-    for (int i=0; i<N; i++)
-      for (int j=0; j<M; j++)
-        for (int d=0; d<D; d++)
-          gX(i,j,d) = (2/ls(d))*(x1(i,d) - x2(j,d));
-    """
-    try:
-        scipy.weave.inline(code, ['x1','x2','gX','ls','M','N','D'], \
-                           type_converters=scipy.weave.converters.blitz, \
-                           compiler='gcc')
-    except:
-    # The C code weave above is 10x faster than this:
-        for i in xrange(0,x1.shape[0]):
-            gX[i,:,:] = 2*(x1[i,:] - x2[:,:])*(1/ls)
-
-    return gX
+    return (x1 * 2/ls**2)[:, np.newaxis, :] - (x2 * 2/ls**2)[np.newaxis, :, :]
 
 def dist_Mahalanobis(U, x1, x2=None):
     W = np.dot(U,U.T)