diff --git a/sql/swh-graph/export/export-graph.sh b/sql/swh-graph/export/export-graph.sh
index 2b9e3d1..05a2790 100755
--- a/sql/swh-graph/export/export-graph.sh
+++ b/sql/swh-graph/export/export-graph.sh
@@ -1,27 +1,28 @@
 #!/bin/bash
 set -e
 
 PSQL_CONN="service=softwareheritage-dev"
 if [ "$1" = "-h" -o "$1" = "--help" ] ; then
     echo "Usage: export-graph.sh [POSTGRES_CONNECTION_STRING]"
     exit 1
 elif [ -n "$1" ] ; then
     PSQL_CONN="$1"
     shift
 fi
 
 tmp_dir=$(mktemp -td swh-graph.XXXXXXXXXX)
 trap "rm -rf ${tmp_dir}" EXIT
 
 fifo="${tmp_dir}/graph.fifo"
+mkfifo "$fifo"
 
 psql "$PSQL_CONN" < export-edges.sql \
     | tee "$fifo" | pigz -c > swh-graph.edges.csv.gz
 
 tr ' ' '\n' < "$fifo" | sort -u | pigz -c > swh-graph.nodes.csv.gz
 
 psql "$PSQL_CONN" < export-origins.sql | pigz -c > swh-graph.origins.csv.gz
 
 echo "All done."
 echo "- graph stored in: swh-graph.{nodes,edges}.csv.gz"
 echo "- origins stored in: swh-graph.origins.csv.gz"