diff --git a/ci-scripts/report-size.sh b/ci-scripts/report-size.sh
index 242f5de..420f844 100755
--- a/ci-scripts/report-size.sh
+++ b/ci-scripts/report-size.sh
@@ -2,21 +2,67 @@
 
 set -eu
 
-package_size_table() {
-	packages=$(nix flake show --json 2>/dev/null | jq --raw-output '.packages."x86_64-linux" | ".#" + keys[]')
-	echo 'Building packages' >&2
-	# we want to split the words as each of them is a different installable
-	# shellcheck disable=SC2086
-	nix build $packages
-	# shellcheck disable=SC2086
-	table=$(nix path-info --size --closure-size --human-readable \
-		$packages |
-		sed 's/^\(\S\+\)\(\s\+\)\(\S\+\)\(\s\+\)\(\S\+\)$/| \1\2| \3 | \4\5 |/')
+echo 'Retrieving Flake information' >&2
+flake_info=$(nix flake show --json 2>/dev/null)
+packages=$(
+	jq --raw-output '.packages."x86_64-linux" | keys[]' <<-EOF
+		$flake_info
+	EOF
+)
+echo "Packages:" >&2
+echo "$packages" >&2
+configurations=$(
+	jq --raw-output '.nixosConfigurations | keys[]' <<-EOF
+		$flake_info
+	EOF
+)
+echo "NixOS Configurations:" >&2
+echo "$configurations" >&2
 
+package_size_table() {
+	table='| Installable | NAR Size | Closure Size |
+|-------------|---------:|-------------:|
+'
+	for package in $packages; do
+		echo "Building $package" >&2
+		path=$(nix build --print-out-paths ".#$package" 2>/dev/null)
+		row=$(nix path-info --size --closure-size --human-readable "$path" 2>/dev/null |
+			sed "s/^\(\S\+\)\(\s\+\)\(\S\+\)\(\s\+\)\(\S\+\)$/| $package | \3 | \4\5 |/")
+		table="$table$row
+"
+	done
+
+	printf '%s' "$table"
+}
+
+configuration_size_table() {
+	table='| NixOS Configuration | NAR Size | Closure Size |
+|-------------|---------:|-------------:|
+'
+	for config in $configurations; do
+		echo "Building $config" >&2
+		path=$(nix build --print-out-paths ".#nixosConfigurations.$config.config.system.build.toplevel" 2>/dev/null)
+		row=$(nix path-info --size --closure-size --human-readable "$path" 2>/dev/null |
+			sed "s/^\(\S\+\)\(\s\+\)\(\S\+\)\(\s\+\)\(\S\+\)$/| $config | \3 | \4 |/")
+		table="$table$row
+"
+	done
+
+	printf '%s' "$table"
+}
+
+markdown() {
 	cat <<-EOF
-		| Nix Store Path | NAR Size | Closure Size |
-		|----------------|---------:|-------------:|
-		$table
+		## Outputs' size
+
+		### NixOS Configurations sizes
+
+		$(configuration_size_table)
+
+
+		### Package sizes
+
+		$(package_size_table)
 	EOF
 }
 
@@ -25,31 +71,21 @@ if [ "${CI-false}" = "true" ]; then
 		"$GITHUB_API_URL/repos/$GITHUB_REPOSITORY/pulls?state=open&sort=recentupdate" \
 		-H 'accept: application/json' |
 		jq --arg head_ref "$GITHUB_HEAD_REF" '.[] | select(.head.ref == $head_ref) | .number')
-	echo "Retrieved index: $pr_number"
-	echo "Expected PR URL: $GITHUB_SERVER_URL/$GITHUB_REPOSITORY/pulls/$pr_number"
-	echo 'Generating comment body'
-	comment=$(
-		cat <<-EOF
-			### NixOS Configurations sizes
-
-			TODO
-
-			### Package sizes
-
-			$(package_size_table)
-		EOF
-	)
-	echo 'Posting comment:'
-	echo "$comment"
-	echo 'Request data:'
+	echo "Retrieved index: $pr_number" >&2
+	echo "Expected PR URL: $GITHUB_SERVER_URL/$GITHUB_REPOSITORY/pulls/$pr_number" >&2
+	echo 'Generating comment body' >&2
+	comment=$(markdown)
+	echo 'Posting comment:' >&2
+	echo "$comment" >&2
+	echo 'Request data:' >&2
 	data=$(echo '{}' | jq --arg comment "$comment" '.body=$comment')
-	echo "$data"
-	curl -o - -v -X 'POST' \
+	echo "$data" >&2
+	curl -o - -X 'POST' \
 		"$GITHUB_API_URL/repos/$GITHUB_REPOSITORY/issues/$pr_number/comments" \
 		-H 'accept: application/json' \
 		-H "Authorization: token $GITHUB_TOKEN" \
 		-H 'Content-Type: application/json' \
 		-d "$data"
 else
-	package_size_table
+	markdown
 fi