diff --git a/generate_graphs.py b/generate_graphs.py
index d954f5f..2dabb66 100755
--- a/generate_graphs.py
+++ b/generate_graphs.py
@@ -29,7 +29,9 @@ def graph(output: Path, rrd: Path, start: str, title: str, unit: str,
     if thermal_mixed:
         args += ["--lower-limit", "0", "--upper-limit", "100", "--rigid"]
     if any(ds.startswith("health_") for ds, _label, _cf in series):
-        args += ["--lower-limit", "0", "--upper-limit", "10", "--rigid"]
+        args += ["--lower-limit", "0", "--upper-limit", "10", "--rigid",
+                 "HRULE:5#9CA3AF:action threshold",
+                 "HRULE:3#DC2626:urgent threshold"]
     value_suffix = "%%" if unit == "%" else ""
     for index, (ds, label, cf) in enumerate(series):
         var = f"v{index}"