diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index 99669a89..0d968faf 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -2301,12 +2301,11 @@ static int calc_group_overhead(ext2_filsys fs, blk64_t grp,
 blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
 {
 	ext2_ino_t inode_count;
-	dgrp_t groups;
+	dgrp_t groups, flex_groups;
 	blk64_t blks_needed, data_blocks;
 	blk64_t grp, data_needed, last_start;
 	blk64_t overhead = 0;
 	int old_desc_blocks;
-	int extra_groups = 0;
 	int flexbg_size = 1 << fs->super->s_log_groups_per_flex;
 
 	/*
@@ -2351,11 +2350,13 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
 	 * inode tables of slack space so the resize operation can be
 	 * guaranteed to finish.
 	 */
-	blks_needed = data_needed;
+	flex_groups = groups;
 	if (fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_FLEX_BG) {
-		extra_groups = flexbg_size - (groups & (flexbg_size - 1));
-		blks_needed += fs->inode_blocks_per_group * extra_groups;
-		extra_groups = groups % flexbg_size;
+		dgrp_t remainder = groups & (flexbg_size - 1);
+
+		flex_groups += flexbg_size - remainder;
+		if (flex_groups > fs->group_desc_count)
+			flex_groups = fs->group_desc_count;
 	}
 
 	/*
@@ -2364,7 +2365,7 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
 	 */
 	data_blocks = groups * EXT2_BLOCKS_PER_GROUP(fs->super);
 	last_start = 0;
-	for (grp = 0; grp < groups; grp++) {
+	for (grp = 0; grp < flex_groups; grp++) {
 		overhead = calc_group_overhead(fs, grp, old_desc_blocks);
 
 		/*
@@ -2372,11 +2373,14 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
 		 * the groups leading up to the last group so we can determine
 		 * how big the last group needs to be
 		 */
-		if (grp != (groups - 1))
+		if (grp < (groups - 1))
 			last_start += EXT2_BLOCKS_PER_GROUP(fs->super) -
 				overhead;
 
-		data_blocks -= overhead;
+		if (data_blocks > overhead)
+			data_blocks -= overhead;
+		else
+			data_blocks = 0;
 	}
 #ifdef RESIZE2FS_DEBUG
 	if (flags & RESIZE_DEBUG_MIN_CALC)
@@ -2388,6 +2392,7 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
 	 * if we need more group descriptors in order to accomodate our data
 	 * then we need to add them here
 	 */
+	blks_needed = data_needed;
 	while (blks_needed > data_blocks) {
 		blk64_t remainder = blks_needed - data_blocks;
 		dgrp_t extra_grps;
@@ -2402,7 +2407,20 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
 		overhead = calc_group_overhead(fs, groups-1, old_desc_blocks);
 		last_start += EXT2_BLOCKS_PER_GROUP(fs->super) - overhead;
 
-		for (grp = groups; grp < groups+extra_grps; grp++) {
+		grp = flex_groups;
+		groups += extra_grps;
+		if (!(fs->super->s_feature_incompat &
+		      EXT4_FEATURE_INCOMPAT_FLEX_BG))
+			flex_groups = groups;
+		else if (groups > flex_groups) {
+			dgrp_t r = groups & (flexbg_size - 1);
+
+			flex_groups = groups + flexbg_size - r;
+			if (flex_groups > fs->group_desc_count)
+				flex_groups = fs->group_desc_count;
+		}
+
+		for (; grp < flex_groups; grp++) {
 			overhead = calc_group_overhead(fs, grp,
 						       old_desc_blocks);
 
@@ -2410,29 +2428,13 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
 			 * again, we need to see how much data we cram into
 			 * all of the groups leading up to the last group
 			 */
-			if (grp != (groups + extra_grps - 1))
+			if (grp < groups - 1)
 				last_start += EXT2_BLOCKS_PER_GROUP(fs->super)
 					- overhead;
 
 			data_blocks -= overhead;
 		}
 
-		groups += extra_grps;
-		extra_groups += extra_grps;
-		if (fs->super->s_feature_incompat
-			& EXT4_FEATURE_INCOMPAT_FLEX_BG
-		    && extra_groups > flexbg_size) {
-			/*
-			 * For ext4 we need to allow for up to a flex_bg worth
-			 * of inode tables of slack space so the resize
-			 * operation can be guaranteed to finish.
-			 */
-			extra_groups = flexbg_size -
-						(groups & (flexbg_size - 1));
-			blks_needed += (fs->inode_blocks_per_group *
-					extra_groups);
-			extra_groups = groups % flexbg_size;
-		}
 #ifdef RESIZE2FS_DEBUG
 		if (flags & RESIZE_DEBUG_MIN_CALC)
 			printf("Added %d extra group(s), "
@@ -2443,7 +2445,14 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
 	}
 
 	/* now for the fun voodoo */
-	overhead = calc_group_overhead(fs, groups-1, old_desc_blocks);
+	grp = groups - 1;
+	if ((fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_FLEX_BG) &&
+	    (grp & ~(flexbg_size - 1)) == 0)
+		grp = grp & ~(flexbg_size - 1);
+	overhead = 0;
+	for (; grp < flex_groups; grp++)
+		overhead += calc_group_overhead(fs, grp, old_desc_blocks);
+
 #ifdef RESIZE2FS_DEBUG
 	if (flags & RESIZE_DEBUG_MIN_CALC)
 		printf("Last group's overhead is %llu\n", overhead);
@@ -2480,10 +2489,15 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
 		printf("Final size of last group is %lld\n", overhead);
 #endif
 
+	/* Add extra slack for bigalloc file systems */
+	if (EXT2FS_CLUSTER_RATIO(fs) > 1)
+		overhead += EXT2FS_CLUSTER_RATIO(fs) * 2;
+
 	/*
-	 * since our last group doesn't have to be BLOCKS_PER_GROUP large, we
-	 * only do groups-1, and then add the number of blocks needed to
-	 * handle the group descriptor metadata+data that we need
+	 * since our last group doesn't have to be BLOCKS_PER_GROUP
+	 * large, we only do groups-1, and then add the number of
+	 * blocks needed to handle the group descriptor metadata+data
+	 * that we need
 	 */
 	blks_needed = (groups-1) * EXT2_BLOCKS_PER_GROUP(fs->super);
 	blks_needed += overhead;
diff --git a/tests/scripts/resize_test b/tests/scripts/resize_test
index b09731c1..c9a7a1c9 100755
--- a/tests/scripts/resize_test
+++ b/tests/scripts/resize_test
@@ -9,6 +9,7 @@ truncate()
 }
 
 resize_test () {
+DBG_FLAGS=63
 
 echo $test_description starting > $LOG
 rm -f $TMPFILE
@@ -57,8 +58,8 @@ rm -f $OUT_TMP
 echo $FSCK -fy $TMPFILE >> $LOG 2>&1 
 $FSCK -fy $TMPFILE >> $LOG 2>&1 
 
-echo $RESIZE2FS $RESIZE2FS_OPTS -d 31 $TMPFILE $SIZE_2 >> $LOG 2>&1
-if ! $RESIZE2FS $RESIZE2FS_OPTS -d 31 $TMPFILE $SIZE_2 >> $LOG 2>&1
+echo $RESIZE2FS $RESIZE2FS_OPTS -d $DBG_FLAGS $TMPFILE $SIZE_2 >> $LOG 2>&1
+if ! $RESIZE2FS $RESIZE2FS_OPTS -d $DBG_FLAGS $TMPFILE $SIZE_2 >> $LOG 2>&1
 then
 	return 1
 fi
@@ -82,8 +83,13 @@ then
 	return 1
 fi
 
-echo $RESIZE2FS $RESIZE2FS_OPTS -d 31 -M $TMPFILE $SIZE_2 >> $LOG 2>&1
-if ! $RESIZE2FS $RESIZE2FS_OPTS -d 31 -M $TMPFILE $SIZE_2 >> $LOG 2>&1
+# Uncomment to grab extra debugging image
+#
+#mv $TMPFILE /tmp/foo.img
+#return 0
+
+echo $RESIZE2FS $RESIZE2FS_OPTS -d $DBG_FLAGS -M $TMPFILE $SIZE_2 >> $LOG 2>&1
+if ! $RESIZE2FS $RESIZE2FS_OPTS -d $DBG_FLAGS -M $TMPFILE $SIZE_2 >> $LOG 2>&1
 then
 	return 1
 fi
@@ -107,8 +113,8 @@ then
 	return 1
 fi
 
-echo $RESIZE2FS $RESIZE2FS_OPTS -d 31 -M $TMPFILE $SIZE_2 >> $LOG 2>&1
-if ! $RESIZE2FS $RESIZE2FS_OPTS -d 31 -M $TMPFILE $SIZE_2 >> $LOG 2>&1
+echo $RESIZE2FS $RESIZE2FS_OPTS -d $DBG_FLAGS -M $TMPFILE $SIZE_2 >> $LOG 2>&1
+if ! $RESIZE2FS $RESIZE2FS_OPTS -d $DBG_FLAGS -M $TMPFILE $SIZE_2 >> $LOG 2>&1
 then
 	return 1
 fi
@@ -132,8 +138,8 @@ then
 	return 1
 fi
 
-echo $RESIZE2FS $RESIZE2FS_OPTS -d 31 -M $TMPFILE $SIZE_2 >> $LOG 2>&1
-if ! $RESIZE2FS $RESIZE2FS_OPTS -d 31 -M $TMPFILE $SIZE_2 >> $LOG 2>&1
+echo $RESIZE2FS $RESIZE2FS_OPTS -d $DBG_FLAGS -M $TMPFILE $SIZE_2 >> $LOG 2>&1
+if ! $RESIZE2FS $RESIZE2FS_OPTS -d $DBG_FLAGS -M $TMPFILE $SIZE_2 >> $LOG 2>&1
 then
 	return 1
 fi