diff --git a/build.sh b/build.sh
index 954d66117..975a09b0b 100755
--- a/build.sh
+++ b/build.sh
@@ -143,9 +143,9 @@ if [ "$RAY_BUILD_PYTHON" == "YES" ]; then
     # Install pickle5-backport.
     TEMP_DIR="$(mktemp -d)"
     pushd "$TEMP_DIR"
-    curl -f -s -L -R -o "pickle5-backport.zip" "https://github.com/suquark/pickle5-backport/archive/8ffe41ceba9d5e2ce8a98190f6b3d2f3325e5a72.zip"
+    curl -f -s -L -R -o "pickle5-backport.zip" "https://github.com/pitrou/pickle5-backport/archive/c0c1a158f59366696161e0dffdd10cfe17601372.zip"
     unzip pickle5-backport.zip
-    pushd pickle5-backport-8ffe41ceba9d5e2ce8a98190f6b3d2f3325e5a72
+    pushd pickle5-backport-c0c1a158f59366696161e0dffdd10cfe17601372
       CC=gcc "$PYTHON_EXECUTABLE" setup.py --quiet bdist_wheel
       unzip -q -o dist/*.whl -d "$pickle5_path"
     popd
diff --git a/python/ray/__init__.py b/python/ray/__init__.py
index de10379a2..0145ac959 100644
--- a/python/ray/__init__.py
+++ b/python/ray/__init__.py
@@ -9,9 +9,13 @@ logger = logging.getLogger(__name__)
 # raylet modules.
 
 if "pickle5" in sys.modules:
-    raise ImportError("Ray must be imported before pickle5 because Ray "
-                      "requires a specific version of pickle5 (which is "
-                      "packaged along with Ray).")
+    import pkg_resources
+    version_info = pkg_resources.require("pickle5")
+    version = tuple(int(n) for n in version_info[0].version.split("."))
+    if version < (0, 0, 10):
+        raise ImportError("You are using an old version of pickle5 that "
+                          "leaks memory, please run 'pip install pickle5 -U' "
+                          "to upgrade")
 
 if "OMP_NUM_THREADS" not in os.environ:
     logger.debug("[ray] Forcing OMP_NUM_THREADS=1 to avoid performance "