Index: /trunk/Ohana/src/libfits/matrix/F_compress_M.c
===================================================================
--- /trunk/Ohana/src/libfits/matrix/F_compress_M.c	(revision 18264)
+++ /trunk/Ohana/src/libfits/matrix/F_compress_M.c	(revision 18265)
@@ -385,5 +385,5 @@
 
     case 2:
-      for (i = 0; i < Nzdata; i+=2) {
+      for (i = 0; i < 2*Nzdata; i+=2) {
 	tmp = zdata[i];
 	zdata[i] = zdata[i+1];
@@ -393,5 +393,5 @@
 
     case 4:
-      for (i = 0; i < Nzdata; i+=4) {
+      for (i = 0; i < 4*Nzdata; i+=4) {
 	tmp = zdata[i+1];
 	zdata[i+1] = zdata[i+2];
@@ -404,5 +404,5 @@
 
     case 8:
-      for (i = 0; i < Nzdata; i+=8) {
+      for (i = 0; i < 8*Nzdata; i+=8) {
 	tmp = zdata[i+0];
 	zdata[i+0] = zdata[i+7];
@@ -464,5 +464,5 @@
   }
   if (!strcasecmp(cmptype, "PLIO_1")) {
-    return (1);
+    return (4);
   }
   if (!strcasecmp(cmptype, "HCOMPRESS_1")) {