diff --git a/splinterpolator.h b/splinterpolator.h
index 04cc819bc8a2998cddbbbc5a7c0237c4f929f3b9..7978800045fe0069470aa1cf632b5089e5e45d80 100644
--- a/splinterpolator.h
+++ b/splinterpolator.h
@@ -1498,7 +1498,7 @@ void Splinterpolator<T>::deconv_along(unsigned int dim)
     ss *= _dim[i];
   }
 
-  if (_nthr==1) { // If we are to run single-threaded
+  if (_nthr<=1) { // If we are to run single-threaded
     SplineColumn  col(mdim,mstep);          // Column helps us do the job
     for (unsigned int l=0; l<rdim[3]; l++) {
       for (unsigned int k=0; k<rdim[2]; k++) {