diff --git a/autoninja b/autoninja
index 06730fa652..7e4a09e88b 100755
--- a/autoninja
+++ b/autoninja
@@ -4,11 +4,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-depot_tools=$(dirname "$0")
-python3="$depot_tools/python-bin/python3"
-
 # Set unique build ID.
-AUTONINJA_BUILD_ID="$($python3 -c "import uuid; print(uuid.uuid4())")"
+AUTONINJA_BUILD_ID="$(python3 -c "import uuid; print(uuid.uuid4())")"
 export AUTONINJA_BUILD_ID
 
 if [ "$NINJA_SUMMARIZE_BUILD" == "1" ]; then
@@ -17,22 +14,23 @@ fi
 
 # Execute whatever is printed by autoninja.py.
 # Also print it to reassure that the right settings are being used.
-command=$($python3 "$depot_tools/autoninja.py" "$@")
+# Don't use python3 because it doesn't work in git bash on Windows.
+command=$(python "$(dirname -- "$0")/autoninja.py" "$@")
 if [ "$NINJA_SUMMARIZE_BUILD" == "1" ]; then
   echo "$command"
 fi
 if eval "$command"; then
   if [ "$NINJA_SUMMARIZE_BUILD" == "1" ]; then
-    $python3 "$depot_tools/post_build_ninja_summary.py" "$@"
+    python3 "$(dirname -- "$0")/post_build_ninja_summary.py" "$@"
   fi
 
   # Collect ninjalog from googler.
-  $python3 "$depot_tools/ninjalog_uploader_wrapper.py" --cmd $command
+  python3 "$(dirname -- "$0")/ninjalog_uploader_wrapper.py" --cmd $command
   exit
 fi
 
 # Collect ninjalog from googler.
-$python3 "$depot_tools/ninjalog_uploader_wrapper.py" --cmd $command
+python3 "$(dirname -- "$0")/ninjalog_uploader_wrapper.py" --cmd $command
 
 # Return an error code of 1 so that if a developer types:
 # "autoninja chrome && chrome" then chrome won't run if the build fails.