diff --git a/piker/ui/_style.py b/piker/ui/_style.py
index 196d6fd8..21fb3e74 100644
--- a/piker/ui/_style.py
+++ b/piker/ui/_style.py
@@ -182,7 +182,7 @@ class DpiAwareFont:
         # always going to hit that error in range mapping from inches:
         # float to px size: int.
         self._font_inches = inches
-        font_size = math.floor(inches * dpi)
+        font_size = math.floor(inches * pdpi)
 
         log.debug(
             f"screen:{screen.name()}\n"
diff --git a/tests/test_dpi_font.py b/tests/test_dpi_font.py
new file mode 100644
index 00000000..04decfcf
--- /dev/null
+++ b/tests/test_dpi_font.py
@@ -0,0 +1,18 @@
+from PyQt6 import QtGui
+from piker.ui._style import DpiAwareFont
+
+class MockScreen:
+    def physicalDotsPerInch(self):
+        return 169  # example HiDPI
+    def logicalDotsPerInch(self):
+        return 96
+    def name(self):
+        return "MockScreen"
+
+# create font instance
+font = DpiAwareFont()
+
+# pass the mock screen to configure_to_dpi
+font.configure_to_dpi(screen=MockScreen())
+
+print("Computed pixel size:", font.px_size)