diff --git a/swh/graph/config.py b/swh/graph/config.py
index 61b24c2..a28fce5 100644
--- a/swh/graph/config.py
+++ b/swh/graph/config.py
@@ -1,110 +1,111 @@
 # Copyright (C) 2019  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import logging
 from pathlib import Path
 import sys
 
 import psutil
 
 
 def find_graph_jar():
     """find swh-graph.jar, containing the Java part of swh-graph
 
     look both in development directories and installed data (for in-production
     deployments who fecthed the JAR from pypi)
 
     """
     swh_graph_root = Path(__file__).parents[2]
     try_paths = [
         swh_graph_root / "java/target/",
         Path(sys.prefix) / "share/swh-graph/",
         Path(sys.prefix) / "local/share/swh-graph/",
     ]
     for path in try_paths:
         glob = list(path.glob("swh-graph-*.jar"))
         if glob:
             if len(glob) > 1:
                 logging.warn(
                     "found multiple swh-graph JARs, " "arbitrarily picking one"
                 )
             logging.info("using swh-graph JAR: {0}".format(glob[0]))
             return str(glob[0])
     raise RuntimeError("swh-graph JAR not found. Have you run `make java`?")
 
 
 def check_config(conf):
     """check configuration and propagate defaults"""
     conf = conf.copy()
     if "batch_size" not in conf:
         conf["batch_size"] = "1000000000"  # 1 billion
     if "max_ram" not in conf:
         conf["max_ram"] = str(psutil.virtual_memory().total)
     if "java_tool_options" not in conf:
         conf["java_tool_options"] = " ".join(
             [
                 "-Xmx{max_ram}",
                 "-XX:PretenureSizeThreshold=512M",
                 "-XX:MaxNewSize=4G",
                 "-XX:+UseLargePages",
                 "-XX:+UseTransparentHugePages",
                 "-XX:+UseNUMA",
                 "-XX:+UseTLAB",
                 "-XX:+ResizeTLAB",
             ]
         )
     conf["java_tool_options"] = conf["java_tool_options"].format(
         max_ram=conf["max_ram"]
     )
     if "java" not in conf:
         conf["java"] = "java"
     if "classpath" not in conf:
         conf["classpath"] = find_graph_jar()
 
     return conf
 
 
 def check_config_compress(config, graph_name, in_dir, out_dir):
     """check compression-specific configuration and initialize its execution
     environment.
     """
     conf = check_config(config)
 
     conf["graph_name"] = graph_name
     conf["in_dir"] = str(in_dir)
     conf["out_dir"] = str(out_dir)
     out_dir.mkdir(parents=True, exist_ok=True)
     if "tmp_dir" not in conf:
         tmp_dir = out_dir / "tmp"
         conf["tmp_dir"] = str(tmp_dir)
     else:
         tmp_dir = Path(conf["tmp_dir"])
     tmp_dir.mkdir(parents=True, exist_ok=True)
 
     if "logback" not in conf:
         logback_confpath = tmp_dir / "logback.xml"
         with open(logback_confpath, "w") as conffile:
             conffile.write(
                 """
 <configuration>
     <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
         <encoder>
             <pattern>%d %r %p [%t] %logger{1} - %m%n</pattern>
         </encoder>
     </appender>
     <root level="INFO">
         <appender-ref ref="STDOUT"/>
     </root>
 </configuration>
 """
             )
         conf["logback"] = str(logback_confpath)
 
     conf["java_tool_options"] += " -Dlogback.configurationFile={logback}"
+    conf["java_tool_options"] += " -Djava.io.tmpdir={tmp_dir}"
     conf["java_tool_options"] = conf["java_tool_options"].format(
-        logback=conf["logback"]
+        logback=conf["logback"], tmp_dir=conf["tmp_dir"],
     )
 
     return conf