diff --git a/fingerprint_client.py b/fingerprint_client.py
index 29c2ebc..11e295c 100644
--- a/fingerprint_client.py
+++ b/fingerprint_client.py
@@ -241,6 +241,20 @@ def playwright_context_kwargs(fp: dict) -> dict:
         kwargs["viewport"] = {"width": outer_w, "height": max(400, outer_h)}
         kwargs["screen"] = {"width": width, "height": height}
 
+    # The device pixel ratio, which Playwright takes as its own context
+    # option and which was previously dropped on the floor. Measured
+    # 2026-09-11 against the live API and a live browser: a fingerprint
+    # stating `deviceScaleFactor: 1.25` produced a browser reporting
+    # `window.devicePixelRatio === 1`, so the identity contradicted itself
+    # on an axis any fingerprinter reads for free -- and a contradiction is
+    # exactly what this flag exists to avoid. Same shape as the three
+    # defects the family notes already list for this file: a key the API
+    # returns that nothing applies. Found by comparing a live browser
+    # against the fingerprint rather than by reading the code.
+    scale = (fp.get("screen") or {}).get("deviceScaleFactor")
+    if isinstance(scale, (int, float)) and not isinstance(scale, bool) and scale > 0:
+        kwargs["device_scale_factor"] = float(scale)
+
     intl = fp.get("intl") or {}
     # The fingerprint's OWN locale. This used to be built as
     # f"en-{country}", which produced "en-DE" for a German fingerprint — an
diff --git a/smoke_test.py b/smoke_test.py
index db22703..8763802 100644
--- a/smoke_test.py
+++ b/smoke_test.py
@@ -1407,7 +1407,8 @@ def wait_for_timeout(self, ms): pass
         from fingerprint_client import playwright_context_kwargs, playwright_init_script
 
         FP = {"id": "fp_test", "country": "us",
-              "screen": {"width": 1920, "height": 1080},
+              "screen": {"width": 1920, "height": 1080,
+                         "deviceScaleFactor": 1},
               "userAgent": {"value": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) Chrome/145.0.0.0"},
               "navigator": {"platform": "Win32", "hardwareConcurrency": 8, "deviceMemory": 8},
               "webgl": {"vendor": 'Google Inc. "quoted"', "renderer": "ANGLE (RTX 3060)"}}
@@ -1421,6 +1422,13 @@ def wait_for_timeout(self, ms): pass
                     and kw["screen"]["width"] == 1920)
 
         js = playwright_init_script(FP)
+        # The device pixel ratio, which Playwright takes as its own option
+        # and which was dropped on the floor until a live browser was
+        # compared against the fingerprint: one stating 1.25 produced a
+        # browser reporting `devicePixelRatio === 1`, an identity
+        # contradicting itself on an axis a fingerprinter reads for free.
+        ok &= check("fingerprint: the device scale factor is carried",
+                    kw.get("device_scale_factor") == 1)
         ok &= check("fingerprint: values are JSON-encoded, so a quote in an API string "
                     "cannot break out of the script",
                     '\\"quoted\\"' in js and "Google Inc. \"quoted\"" not in js)