diff --git a/src/H5Pdcpl.c b/src/H5Pdcpl.c
index f3acfe221e..067751768f 100644
--- a/src/H5Pdcpl.c
+++ b/src/H5Pdcpl.c
@@ -455,9 +455,6 @@ H5P__dcrt_layout_enc(const void *value, void **_pp, size_t *size)
             /* number of entries */
             *size += (size_t)8;
 
-            /* NULL pointer to pass to H5S_encode */
-            tmp_p = NULL;
-
             /* Iterate over entries */
             for(u = 0; u < layout->storage.u.virt.list_nused; u++) {
                 /* Source file name */
@@ -470,12 +467,14 @@ H5P__dcrt_layout_enc(const void *value, void **_pp, size_t *size)
 
                 /* Source selection */
                 tmp_size = (size_t)0;
+                tmp_p = NULL;
                 if(H5S_encode(layout->storage.u.virt.list[u].source_select, &tmp_p, &tmp_size) < 0)
                     HGOTO_ERROR(H5E_PLIST, H5E_CANTENCODE, FAIL, "unable to serialize source selection")
                 *size += tmp_size;
 
                 /* Virtual dataset selection */
                 tmp_size = (size_t)0;
+                tmp_p = NULL;
                 if(H5S_encode(layout->storage.u.virt.list[u].source_dset.virtual_select, &tmp_p, &tmp_size) < 0)
                     HGOTO_ERROR(H5E_PLIST, H5E_CANTENCODE, FAIL, "unable to serialize virtual selection")
                 *size += tmp_size;
diff --git a/src/H5S.c b/src/H5S.c
index af7d3951fd..738a7da294 100644
--- a/src/H5S.c
+++ b/src/H5S.c
@@ -1577,7 +1577,6 @@ herr_t
 H5S_encode(H5S_t *obj, unsigned char **p, size_t *nalloc)
 {
     H5F_t       *f = NULL;      /* Fake file structure*/
-    unsigned char *pp = (*p);   /* Local pointer for decoding */
     size_t      extent_size;    /* Size of serialized dataspace extent */
     hssize_t    sselect_size;   /* Signed size of serialized dataspace selection */
     size_t      select_size;    /* Size of serialized dataspace selection */
@@ -1600,9 +1599,11 @@ H5S_encode(H5S_t *obj, unsigned char **p, size_t *nalloc)
 
     /* Verify the size of buffer.  If it's not big enough, simply return the
      * right size without filling the buffer. */
-    if(!pp || *nalloc < (extent_size + select_size + 1 + 1 + 1 + 4))
+    if(!*p || *nalloc < (extent_size + select_size + 1 + 1 + 1 + 4))
         *nalloc = extent_size + select_size + 1 + 1 + 1 + 4;
     else {
+        unsigned char *pp = (*p);   /* Local pointer for decoding */
+
         /* Encode the type of the information */
         *pp++ = H5O_SDSPACE_ID;