diff --git a/src/kmeans.jl b/src/kmeans.jl
index 13a5313..08ef801 100644
--- a/src/kmeans.jl
+++ b/src/kmeans.jl
@@ -94,7 +94,7 @@ Allocationless calculation of square eucledean distance between vectors X1[:, i1
 function distance(X1, X2, i1, i2)
     d = 0.0
     # TODO: break of the loop if d is larger than threshold (known minimum disatnce)
-    @inbounds for i in axes(X1, 1)
+    @inbounds @simd for i in axes(X1, 1)
         d += (X1[i, i1] - X2[i, i2])^2
     end