diff --git a/include/finufft/finufft_core.h b/include/finufft/finufft_core.h
index cdfa4ab33..8f473dc86 100644
--- a/include/finufft/finufft_core.h
+++ b/include/finufft/finufft_core.h
@@ -171,10 +171,10 @@ template<typename TF> struct FINUFFT_PLAN_T { // the main plan object, fully C++
   BIGINT mu;               // number of modes in z (3) direction = N3
   BIGINT N;                // total # modes (prod of above three)
 
-  BIGINT nf1;              // size of internal fine grid in x (1) direction
-  BIGINT nf2;              // " y (2)
-  BIGINT nf3;              // " z (3)
-  BIGINT nf;               // total # fine grid points (product of the above three)
+  BIGINT nf1 = 1;          // size of internal fine grid in x (1) direction
+  BIGINT nf2 = 1;          // " y (2)
+  BIGINT nf3 = 1;          // " z (3)
+  BIGINT nf  = 1;          // total # fine grid points (product of the above three)
 
   int fftSign;             // sign in exponential for NUFFT defn, guaranteed to be +-1
 
@@ -182,15 +182,18 @@ template<typename TF> struct FINUFFT_PLAN_T { // the main plan object, fully C++
   std::vector<TF> phiHat2; // " y-axis.
   std::vector<TF> phiHat3; // " z-axis.
 
-  TC *fwBatch = nullptr;   // (batches of) fine grid(s) for FFTW to plan
-                           // & act on. Usually the largest working array
+  TC *fwBatch = nullptr;   // (batches of) fine grid(s) for the FFT to plan
+                           // & act on. Usually the largest working array.
+                           // Unfortunately this can't be a vector, since
+                           // in the presence of FFTW it must be allocated
+                           // by fftw_malloc.
 
   std::vector<BIGINT> sortIndices; // precomputed NU pt permutation, speeds spread/interp
   bool didSort;                    // whether binsorting used (false: identity perm used)
 
   TF *X = nullptr, *Y = nullptr, *Z = nullptr; // for t1,2: ptr to user-supplied NU pts
-                                               // (no new allocs). for t3: allocated as
-                                               // "primed" (scaled) src pts x'_j, etc
+                                               // (no new allocs). for t3: points to
+                                               // "primed" (scaled) Xp, Yp, Zp
 
   // type 3 specific
   TF *S = nullptr, *T = nullptr, *U = nullptr; // pointers to user's target NU pts arrays
@@ -198,8 +201,8 @@ template<typename TF> struct FINUFFT_PLAN_T { // the main plan object, fully C++
   std::vector<TC> prephase;                    // pre-phase, for all input NU pts
   std::vector<TC> deconv;     // reciprocal of kernel FT, phase, all output NU pts
   std::vector<TC> CpBatch;    // working array of prephased strengths
-  std::vector<TF> Sp, Tp, Up; // internal primed targs (s'_k, etc),
-                              // allocated
+  std::vector<TF> Xp, Yp, Zp; // internal primed NU points (x'_j, etc)
+  std::vector<TF> Sp, Tp, Up; // internal primed targs (s'_k, etc)
   type3params<TF> t3P;        // groups together type 3 shift, scale, phase, parameters
   std::unique_ptr<FINUFFT_PLAN_T<TF>> innerT2plan; // ptr used for type 2 in step 2 of
                                                    // type 3
diff --git a/src/finufft_core.cpp b/src/finufft_core.cpp
index 2130cfd8a..464ac5446 100644
--- a/src/finufft_core.cpp
+++ b/src/finufft_core.cpp
@@ -641,18 +641,10 @@ FINUFFT_PLAN_T<TF>::FINUFFT_PLAN_T(int type_, int dim_, const BIGINT *n_modes, i
   if (ier > 1) // proceed if success or warning
     throw int(ier);
 
-  // set others as defaults (or unallocated for arrays)...
-  X   = nullptr;
-  Y   = nullptr;
-  Z   = nullptr;
-  nf1 = 1;
-  nf2 = 1;
-  nf3 = 1; // crucial to leave as 1 for unused dims
-
   //  ------------------------ types 1,2: planning needed ---------------------
   if (type == 1 || type == 2) {
 
-    int nthr_fft = nthr; // give FFTW all threads (or use o.spread_thread?)
+    int nthr_fft = nthr; // give FFT all threads (or use o.spread_thread?)
                          // Note: batchSize not used since might be only 1.
 
     spopts.spread_direction = type;
@@ -885,18 +877,19 @@ int FINUFFT_PLAN_T<TF>::setpts(BIGINT nj, TF *xj, TF *yj, TF *zj, BIGINT nk, TF
     // printf("fwbatch, cpbatch ptrs: %llx %llx\n",fwBatch,CpBatch);
 
     // alloc rescaled NU src pts x'_j (in X etc), rescaled NU targ pts s'_k ...
-    // FIXME: should use realloc
-    if (X) delete[] X;
-    X = new TF[nj];
+    // We do this by resizing Xp, Yp, and Zp, and pointing X, Y, Z to their data;
+    // this avoids any need for explicit cleanup.
+    Xp.resize(nj);
+    X = Xp.data();
     Sp.resize(nk);
     if (d > 1) {
-      if (Y) delete[] Y;
-      Y = new TF[nj];
+      Yp.resize(nj);
+      Y = Yp.data();
       Tp.resize(nk);
     }
     if (d > 2) {
-      if (Z) delete[] Z;
-      Z = new TF[nj];
+      Zp.resize(nj);
+      Z = Zp.data();
       Up.resize(nk);
     }
 
@@ -1173,11 +1166,6 @@ template<typename TF> FINUFFT_PLAN_T<TF>::~FINUFFT_PLAN_T() {
   // Thus either each thing free'd here is guaranteed to be nullptr or correctly
   // allocated.
   if (fftPlan) fftPlan->free(fwBatch); // free the big FFT (or t3 spread) working array
-  if (type == 3) {
-    delete[] X;
-    delete[] Y;
-    delete[] Z;
-  }
 }
 template FINUFFT_PLAN_T<float>::~FINUFFT_PLAN_T();
 template FINUFFT_PLAN_T<double>::~FINUFFT_PLAN_T();