diff --git a/jdapistd.c b/jdapistd.c
index d8ea7add4..2343da5c3 100644
--- a/jdapistd.c
+++ b/jdapistd.c
@@ -204,7 +204,7 @@ jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
   }
 
   /* Verify that at least one iMCU row can be returned. */
-  lines_per_iMCU_row = cinfo->max_v_samp_factor * _min_DCT_scaled_size;
+  lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size;
   if (max_lines < lines_per_iMCU_row)
     ERREXIT(cinfo, JERR_BUFFER_SIZE);
 
diff --git a/jdcoefct.c b/jdcoefct.c
index 80fc89d13..48a9fc6f8 100644
--- a/jdcoefct.c
+++ b/jdcoefct.c
@@ -192,7 +192,7 @@ decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 	useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
 						    : compptr->last_col_width;
 	output_ptr = output_buf[compptr->component_index] +
-	  yoffset * _DCT_scaled_size;
+	  yoffset * compptr->_DCT_scaled_size;
 	start_col = MCU_col_num * compptr->MCU_sample_width;
 	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
 	  if (cinfo->input_iMCU_row < last_iMCU_row ||
@@ -202,11 +202,11 @@ decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 	      (*inverse_DCT) (cinfo, compptr,
 			      (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
 			      output_ptr, output_col);
-	      output_col += _DCT_scaled_size;
+	      output_col += compptr->_DCT_scaled_size;
 	    }
 	  }
 	  blkn += compptr->MCU_width;
-	  output_ptr += _DCT_scaled_size;
+	  output_ptr += compptr->_DCT_scaled_size;
 	}
       }
     }
@@ -367,9 +367,9 @@ decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 	(*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
 			output_ptr, output_col);
 	buffer_ptr++;
-	output_col += _DCT_scaled_size;
+	output_col += compptr->_DCT_scaled_size;
       }
-      output_ptr += _DCT_scaled_size;
+      output_ptr += compptr->_DCT_scaled_size;
     }
   }
 
@@ -662,9 +662,9 @@ decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 	DC4 = DC5; DC5 = DC6;
 	DC7 = DC8; DC8 = DC9;
 	buffer_ptr++, prev_block_row++, next_block_row++;
-	output_col += _DCT_scaled_size;
+	output_col += compptr->_DCT_scaled_size;
       }
-      output_ptr += _DCT_scaled_size;
+      output_ptr += compptr->_DCT_scaled_size;
     }
   }
 
diff --git a/jddctmgr.c b/jddctmgr.c
index 70f4f01df..044e46947 100644
--- a/jddctmgr.c
+++ b/jddctmgr.c
@@ -102,7 +102,7 @@ start_pass (j_decompress_ptr cinfo)
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     /* Select the proper IDCT routine for this component's scaling */
-    switch (_DCT_scaled_size) {
+    switch (compptr->_DCT_scaled_size) {
 #ifdef IDCT_SCALING_SUPPORTED
     case 1:
       method_ptr = jpeg_idct_1x1;
@@ -158,7 +158,7 @@ start_pass (j_decompress_ptr cinfo)
       }
       break;
     default:
-      ERREXIT1(cinfo, JERR_BAD_DCTSIZE, _DCT_scaled_size);
+      ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->_DCT_scaled_size);
       break;
     }
     idct->pub.inverse_DCT[ci] = method_ptr;
diff --git a/jdhuff.c b/jdhuff.c
index 3aa8dad74..ab8e25444 100644
--- a/jdhuff.c
+++ b/jdhuff.c
@@ -139,7 +139,7 @@ start_pass_huff_decoder (j_decompress_ptr cinfo)
     if (compptr->component_needed) {
       entropy->dc_needed[blkn] = TRUE;
       /* we don't need the ACs if producing a 1/8th-size image */
-      entropy->ac_needed[blkn] = (_DCT_scaled_size > 1);
+      entropy->ac_needed[blkn] = (compptr->_DCT_scaled_size > 1);
     } else {
       entropy->dc_needed[blkn] = entropy->ac_needed[blkn] = FALSE;
     }
diff --git a/jdinput.c b/jdinput.c
index c75fd5c11..9fcd089d3 100644
--- a/jdinput.c
+++ b/jdinput.c
@@ -228,7 +228,7 @@ per_scan_setup (j_decompress_ptr cinfo)
     compptr->MCU_width = 1;
     compptr->MCU_height = 1;
     compptr->MCU_blocks = 1;
-    compptr->MCU_sample_width = _DCT_scaled_size;
+    compptr->MCU_sample_width = compptr->_DCT_scaled_size;
     compptr->last_col_width = 1;
     /* For noninterleaved scans, it is convenient to define last_row_height
      * as the number of block rows present in the last iMCU row.
@@ -264,7 +264,7 @@ per_scan_setup (j_decompress_ptr cinfo)
       compptr->MCU_width = compptr->h_samp_factor;
       compptr->MCU_height = compptr->v_samp_factor;
       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
-      compptr->MCU_sample_width = compptr->MCU_width * _DCT_scaled_size;
+      compptr->MCU_sample_width = compptr->MCU_width * compptr->_DCT_scaled_size;
       /* Figure number of non-dummy blocks in last MCU column & row */
       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
       if (tmp == 0) tmp = compptr->MCU_width;
diff --git a/jdmainct.c b/jdmainct.c
index 8d298e1b5..67f62153e 100644
--- a/jdmainct.c
+++ b/jdmainct.c
@@ -163,7 +163,7 @@ alloc_funny_pointers (j_decompress_ptr cinfo)
 {
   my_main_ptr main = (my_main_ptr) cinfo->main;
   int ci, rgroup;
-  int M = _min_DCT_scaled_size;
+  int M = cinfo->_min_DCT_scaled_size;
   jpeg_component_info *compptr;
   JSAMPARRAY xbuf;
 
@@ -177,8 +177,8 @@ alloc_funny_pointers (j_decompress_ptr cinfo)
 
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
-    rgroup = (compptr->v_samp_factor * _DCT_scaled_size) /
-      _min_DCT_scaled_size; /* height of a row group of component */
+    rgroup = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
+      cinfo->_min_DCT_scaled_size; /* height of a row group of component */
     /* Get space for pointer lists --- M+4 row groups in each list.
      * We alloc both pointer lists with one call to save a few cycles.
      */
@@ -204,14 +204,14 @@ make_funny_pointers (j_decompress_ptr cinfo)
 {
   my_main_ptr main = (my_main_ptr) cinfo->main;
   int ci, i, rgroup;
-  int M = _min_DCT_scaled_size;
+  int M = cinfo->_min_DCT_scaled_size;
   jpeg_component_info *compptr;
   JSAMPARRAY buf, xbuf0, xbuf1;
 
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
-    rgroup = (compptr->v_samp_factor * _DCT_scaled_size) /
-      _min_DCT_scaled_size; /* height of a row group of component */
+    rgroup = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
+      cinfo->_min_DCT_scaled_size; /* height of a row group of component */
     xbuf0 = main->xbuffer[0][ci];
     xbuf1 = main->xbuffer[1][ci];
     /* First copy the workspace pointers as-is */
@@ -244,14 +244,14 @@ set_wraparound_pointers (j_decompress_ptr cinfo)
 {
   my_main_ptr main = (my_main_ptr) cinfo->main;
   int ci, i, rgroup;
-  int M = _min_DCT_scaled_size;
+  int M = cinfo->_min_DCT_scaled_size;
   jpeg_component_info *compptr;
   JSAMPARRAY xbuf0, xbuf1;
 
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
-    rgroup = (compptr->v_samp_factor * _DCT_scaled_size) /
-      _min_DCT_scaled_size; /* height of a row group of component */
+    rgroup = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
+      cinfo->_min_DCT_scaled_size; /* height of a row group of component */
     xbuf0 = main->xbuffer[0][ci];
     xbuf1 = main->xbuffer[1][ci];
     for (i = 0; i < rgroup; i++) {
@@ -279,8 +279,8 @@ set_bottom_pointers (j_decompress_ptr cinfo)
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     /* Count sample rows in one iMCU row and in one row group */
-    iMCUheight = compptr->v_samp_factor * _DCT_scaled_size;
-    rgroup = iMCUheight / _min_DCT_scaled_size;
+    iMCUheight = compptr->v_samp_factor * compptr->_DCT_scaled_size;
+    rgroup = iMCUheight / cinfo->_min_DCT_scaled_size;
     /* Count nondummy sample rows remaining for this component */
     rows_left = (int) (compptr->downsampled_height % (JDIMENSION) iMCUheight);
     if (rows_left == 0) rows_left = iMCUheight;
@@ -359,7 +359,7 @@ process_data_simple_main (j_decompress_ptr cinfo,
   }
 
   /* There are always min_DCT_scaled_size row groups in an iMCU row. */
-  rowgroups_avail = (JDIMENSION) _min_DCT_scaled_size;
+  rowgroups_avail = (JDIMENSION) cinfo->_min_DCT_scaled_size;
   /* Note: at the bottom of the image, we may pass extra garbage row groups
    * to the postprocessor.  The postprocessor has to check for bottom
    * of image anyway (at row resolution), so no point in us doing it too.
@@ -419,7 +419,7 @@ process_data_context_main (j_decompress_ptr cinfo,
   case CTX_PREPARE_FOR_IMCU:
     /* Prepare to process first M-1 row groups of this iMCU row */
     main->rowgroup_ctr = 0;
-    main->rowgroups_avail = (JDIMENSION) (_min_DCT_scaled_size - 1);
+    main->rowgroups_avail = (JDIMENSION) (cinfo->_min_DCT_scaled_size - 1);
     /* Check for bottom of image: if so, tweak pointers to "duplicate"
      * the last sample row, and adjust rowgroups_avail to ignore padding rows.
      */
@@ -442,8 +442,8 @@ process_data_context_main (j_decompress_ptr cinfo,
     main->buffer_full = FALSE;
     /* Still need to process last row group of this iMCU row, */
     /* which is saved at index M+1 of the other xbuffer */
-    main->rowgroup_ctr = (JDIMENSION) (_min_DCT_scaled_size + 1);
-    main->rowgroups_avail = (JDIMENSION) (_min_DCT_scaled_size + 2);
+    main->rowgroup_ctr = (JDIMENSION) (cinfo->_min_DCT_scaled_size + 1);
+    main->rowgroups_avail = (JDIMENSION) (cinfo->_min_DCT_scaled_size + 2);
     main->context_state = CTX_POSTPONED_ROW;
   }
 }
@@ -494,21 +494,21 @@ jinit_d_main_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
    * ngroups is the number of row groups we need.
    */
   if (cinfo->upsample->need_context_rows) {
-    if (_min_DCT_scaled_size < 2) /* unsupported, see comments above */
+    if (cinfo->_min_DCT_scaled_size < 2) /* unsupported, see comments above */
       ERREXIT(cinfo, JERR_NOTIMPL);
     alloc_funny_pointers(cinfo); /* Alloc space for xbuffer[] lists */
-    ngroups = _min_DCT_scaled_size + 2;
+    ngroups = cinfo->_min_DCT_scaled_size + 2;
   } else {
-    ngroups = _min_DCT_scaled_size;
+    ngroups = cinfo->_min_DCT_scaled_size;
   }
 
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
-    rgroup = (compptr->v_samp_factor * _DCT_scaled_size) /
-      _min_DCT_scaled_size; /* height of a row group of component */
+    rgroup = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
+      cinfo->_min_DCT_scaled_size; /* height of a row group of component */
     main->buffer[ci] = (*cinfo->mem->alloc_sarray)
 			((j_common_ptr) cinfo, JPOOL_IMAGE,
-			 compptr->width_in_blocks * _DCT_scaled_size,
+			 compptr->width_in_blocks * compptr->_DCT_scaled_size,
 			 (JDIMENSION) (rgroup * ngroups));
   }
 }
diff --git a/jdmaster.c b/jdmaster.c
index 3985c73cf..38b7dd0cb 100644
--- a/jdmaster.c
+++ b/jdmaster.c
@@ -69,17 +69,10 @@ use_merged_upsample (j_decompress_ptr cinfo)
       cinfo->comp_info[2].v_samp_factor != 1)
     return FALSE;
   /* furthermore, it doesn't work if we've scaled the IDCTs differently */
-#if JPEG_LIB_VERSION >= 70
-  if (cinfo->comp_info[0].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
-      cinfo->comp_info[1].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
-      cinfo->comp_info[2].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size)
-    return FALSE;
-#else
-  if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
-      cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
-      cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size)
+  if (cinfo->comp_info[0]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
+      cinfo->comp_info[1]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
+      cinfo->comp_info[2]._DCT_scaled_size != cinfo->_min_DCT_scaled_size)
     return FALSE;
-#endif
   /* ??? also need to test for upsample-time rescaling, when & if supported */
   return TRUE;			/* by golly, it'll work... */
 #else
@@ -161,12 +154,12 @@ jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
    */
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
-    int ssize = _min_DCT_scaled_size;
+    int ssize = cinfo->_min_DCT_scaled_size;
     while (ssize < DCTSIZE &&
 	   (compptr->h_samp_factor * ssize * 2 <=
-	    cinfo->max_h_samp_factor * _min_DCT_scaled_size) &&
+	    cinfo->max_h_samp_factor * cinfo->_min_DCT_scaled_size) &&
 	   (compptr->v_samp_factor * ssize * 2 <=
-	    cinfo->max_v_samp_factor * _min_DCT_scaled_size)) {
+	    cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size)) {
       ssize = ssize * 2;
     }
 #if JPEG_LIB_VERSION >= 70
@@ -184,11 +177,11 @@ jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
     /* Size in samples, after IDCT scaling */
     compptr->downsampled_width = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width *
-		    (long) (compptr->h_samp_factor * _DCT_scaled_size),
+		    (long) (compptr->h_samp_factor * compptr->_DCT_scaled_size),
 		    (long) (cinfo->max_h_samp_factor * DCTSIZE));
     compptr->downsampled_height = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height *
-		    (long) (compptr->v_samp_factor * _DCT_scaled_size),
+		    (long) (compptr->v_samp_factor * compptr->_DCT_scaled_size),
 		    (long) (cinfo->max_v_samp_factor * DCTSIZE));
   }
 
diff --git a/jdsample.c b/jdsample.c
index 5f6ffbec4..1864dd6b8 100644
--- a/jdsample.c
+++ b/jdsample.c
@@ -422,7 +422,7 @@ jinit_upsampler (j_decompress_ptr cinfo)
   /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1,
    * so don't ask for it.
    */
-  do_fancy = cinfo->do_fancy_upsampling && _min_DCT_scaled_size > 1;
+  do_fancy = cinfo->do_fancy_upsampling && cinfo->_min_DCT_scaled_size > 1;
 
   /* Verify we can handle the sampling factors, select per-component methods,
    * and create storage as needed.
@@ -432,10 +432,10 @@ jinit_upsampler (j_decompress_ptr cinfo)
     /* Compute size of an "input group" after IDCT scaling.  This many samples
      * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
      */
-    h_in_group = (compptr->h_samp_factor * _DCT_scaled_size) /
-		 _min_DCT_scaled_size;
-    v_in_group = (compptr->v_samp_factor * _DCT_scaled_size) /
-		 _min_DCT_scaled_size;
+    h_in_group = (compptr->h_samp_factor * compptr->_DCT_scaled_size) /
+		 cinfo->_min_DCT_scaled_size;
+    v_in_group = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
+		 cinfo->_min_DCT_scaled_size;
     h_out_group = cinfo->max_h_samp_factor;
     v_out_group = cinfo->max_v_samp_factor;
     upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
diff --git a/jpegcomp.h b/jpegcomp.h
index 8891fb578..be5eb34a7 100644
--- a/jpegcomp.h
+++ b/jpegcomp.h
@@ -10,9 +10,9 @@
  */
 
 #if JPEG_LIB_VERSION >= 70
-#define _DCT_scaled_size compptr->DCT_h_scaled_size
-#define _min_DCT_scaled_size cinfo->min_DCT_h_scaled_size
+#define _DCT_scaled_size DCT_h_scaled_size
+#define _min_DCT_scaled_size min_DCT_h_scaled_size
 #else
-#define _DCT_scaled_size compptr->DCT_scaled_size
-#define _min_DCT_scaled_size cinfo->min_DCT_scaled_size
+#define _DCT_scaled_size DCT_scaled_size
+#define _min_DCT_scaled_size min_DCT_scaled_size
 #endif