diff --git a/include/photospline/detail/convolve.h b/include/photospline/detail/convolve.h
index 33ffcba..6a5b597 100644
--- a/include/photospline/detail/convolve.h
+++ b/include/photospline/detail/convolve.h
@@ -144,6 +144,9 @@ void splinetable<Alloc>::convolve(const uint32_t dim, const double* conv_knots,
 		double* src = (i!=dim ? knots_store[i].get() : rho);
 		std::copy(src,src+nknots[i],&knots[i][0]);
 	}
+
+	// Update knot separations
+	dknot_bounds();
 	
 	/*
 	 * NB: A monotonic function remains monotonic after convolution
diff --git a/include/photospline/detail/permute.h b/include/photospline/detail/permute.h
index ffac2aa..b1cf166 100644
--- a/include/photospline/detail/permute.h
+++ b/include/photospline/detail/permute.h
@@ -82,8 +82,11 @@ void splinetable<Alloc>::permuteDimensions(const std::vector<size_t>& permutatio
 		extents[i][1]=t_extents[i][1];
 	}
 	std::copy(t_coefficients.get(),t_coefficients.get()+ncoeffs,coefficients);
+
+	// Update knot separations
+	dknot_bounds();
 }
 	
 } //namespace photospline
 
-#endif
\ No newline at end of file
+#endif
diff --git a/include/photospline/splinetable.h b/include/photospline/splinetable.h
index 9538397..44c8e9e 100644
--- a/include/photospline/splinetable.h
+++ b/include/photospline/splinetable.h
@@ -187,6 +187,12 @@ class splinetable{
         snew->nknots = snew->allocate<uint64_t>(s2->ndim);
         std::copy_n(s2->nknots,s2->ndim,snew->nknots);
 
+        snew->rmin_sep = snew->allocate<double>(s2->ndim);
+        std::copy_n(s2->rmin_sep,s2->ndim,snew->rmin_sep);
+
+        snew->rmax_sep = snew->allocate<double>(s2->ndim);
+        std::copy_n(s2->rmax_sep,s2->ndim,snew->rmax_sep);
+
         snew->knots = snew->allocate<double_ptr>(s2->ndim);
         for(unsigned int i=0; i<s2->ndim; i++){
           snew->knots[i] = snew->allocate<double>(s2->nknots[i]+2*s2->order[i]) + s2->order[i];
@@ -211,8 +217,6 @@ class splinetable{
         }
 
         snew->periods = NULL;
-        snew->rmin_sep = NULL;
-        snew->rmax_sep = NULL;
         snew->naux = 0;
         snew->aux = NULL;
 
@@ -273,6 +277,8 @@ class splinetable{
       lastKnots[nknots[inputDim]-1]=2*lastKnots[nknots[inputDim]-2]-lastKnots[nknots[inputDim]-3];
     }
 
+    rmin_sep=allocate<double>(ndim);
+    rmax_sep=allocate<double>(ndim);
 		dknot_bounds();
 
     //set naxes