diff --git a/src/gui/ModemChrome.cpp b/src/gui/ModemChrome.cpp
index 18de184907..ce6cb8bb45 100644
--- a/src/gui/ModemChrome.cpp
+++ b/src/gui/ModemChrome.cpp
@@ -396,12 +396,15 @@ QScrollBar::sub-line:vertical {
     // The canon look's check boxes and radio buttons are the painted canon
     // indicators alone: the sheet's own indicator rules come out first, since
     // its :checked ones are more specific than the generic indicator rule and
-    // would draw a border around the image. Lists (the AetherRX/AetherTX
-    // profile libraries) sit on a nested card; the modem look leaves them to
-    // the application sheet.
+    // would draw a border around the image. A rule body here holds {{token}}
+    // placeholders, so it ends at the first brace outside one: ending at the
+    // first "}" would stop inside a token and leave the rest of the rule
+    // behind, breaking the sheet so the painted indicators never apply. Lists
+    // (the AetherRX/AetherTX profile libraries) sit on a nested card; the
+    // modem look leaves them to the application sheet.
     if (look == Look::Canon) {
-        static const QRegularExpression ownIndicatorRules(
-            QStringLiteral(R"((?:QCheckBox|QRadioButton)::indicator[^{]*\{[^}]*\}\s*)"));
+        static const QRegularExpression ownIndicatorRules(QStringLiteral(
+            R"((?:QCheckBox|QRadioButton)::indicator[^{]*\{(?:\{\{[^{}]*\}\}|[^{}])*\}\s*)"));
         sheet.remove(ownIndicatorRules);
         sheet += canonIndicatorRules();
         sheet += QStringLiteral(
diff --git a/tests/modem_chrome_test.cpp b/tests/modem_chrome_test.cpp
index 50d982e6ac..5fe1ca33d3 100644
--- a/tests/modem_chrome_test.cpp
+++ b/tests/modem_chrome_test.cpp
@@ -19,11 +19,18 @@
 #include "TestSettingsProfile.h"
 
 #include <QApplication>
+#include <QCheckBox>
+#include <QColor>
+#include <QImage>
+#include <QRadioButton>
+#include <QStyle>
+#include <QStyleOptionButton>
 #include <QRegularExpression>
 #include <QString>
 #include <QtTest>
 
 #include <cstdio>
+#include <type_traits>
 
 using namespace AetherSDR;
 
@@ -38,6 +45,8 @@ private slots:
     void everyThemeTokenInTheSheetResolves();
     void checkedLosesToDisabled();
     void canonLookPaintsItsIndicators();
+    void canonSheetLeavesNoRuleFragments();
+    void canonIndicatorsRenderTheirImages();
 };
 
 namespace {
@@ -51,6 +60,29 @@ int baseFontSize(const QString& sheet)
     return m.hasMatch() ? m.captured(1).toInt() : -1;
 }
 
+// The pixels of `button`'s indicator under `sheet` (theme-resolved), so two
+// sheets can be compared by what they draw rather than by their text.
+template <typename Button>
+QImage indicatorPixels(const QString& sheet, bool checked)
+{
+    Button button(QStringLiteral("x"));
+    button.setStyleSheet(ThemeManager::instance().resolve(sheet));
+    button.setChecked(checked);
+    button.ensurePolished();
+    button.resize(button.sizeHint());
+    QStyleOptionButton option;
+    option.initFrom(&button);
+    const auto element = std::is_same_v<Button, QCheckBox> ? QStyle::SE_CheckBoxIndicator
+                                                           : QStyle::SE_RadioButtonIndicator;
+    const QRect rect = button.style()->subElementRect(element, &option, &button);
+    // Over one fixed backdrop, without the widget's own background, so only
+    // what the indicator draws can differ.
+    QImage pixels(rect.size(), QImage::Format_ARGB32_Premultiplied);
+    pixels.fill(QColor(0x40, 0x20, 0x60));
+    button.render(&pixels, QPoint(), QRegion(rect), QWidget::DrawChildren);
+    return pixels;
+}
+
 } // namespace
 
 void ModemChromeTest::bothScalesCarryEveryStructuralSelector()
@@ -134,6 +166,46 @@ void ModemChromeTest::canonLookPaintsItsIndicators()
     }
 }
 
+// Taking the sheet's own indicator rules out must take each whole rule. Their
+// bodies hold {{token}} placeholders, and a rule cut at the first "}" leaves
+// "}};" fragments that break the sheet, so the painted indicators never apply.
+void ModemChromeTest::canonSheetLeavesNoRuleFragments()
+{
+    static const QRegularExpression token(QStringLiteral(R"(\{\{[^{}]*\}\})"));
+    for (const auto scale : {ModemChrome::Scale::Dialog, ModemChrome::Scale::Compact}) {
+        QString structure = ModemChrome::styleSheet(scale, ModemChrome::Look::Canon);
+        structure.replace(token, QStringLiteral("token"));
+        int depth = 0;
+        for (const QChar ch : structure) {
+            if (ch == QLatin1Char('{')) {
+                QVERIFY2(++depth == 1, "a rule opens inside another rule");
+            } else if (ch == QLatin1Char('}')) {
+                QVERIFY2(--depth == 0, "a closing brace has no rule to close");
+            }
+        }
+        QCOMPARE(depth, 0);
+    }
+}
+
+// In the canon look a check box and a radio button draw exactly what the
+// painted canon indicators draw on their own, checked and unchecked: the rest
+// of the sheet neither hides the images nor draws over them.
+void ModemChromeTest::canonIndicatorsRenderTheirImages()
+{
+    const QString indicators = canonIndicatorRules();
+    QVERIFY(!indicators.isEmpty());
+    const QString canon = ModemChrome::styleSheet(ModemChrome::Scale::Dialog,
+                                                  ModemChrome::Look::Canon);
+    for (const bool checked : {false, true}) {
+        const QImage box = indicatorPixels<QCheckBox>(canon, checked);
+        QVERIFY(!box.isNull());
+        QCOMPARE(box, indicatorPixels<QCheckBox>(indicators, checked));
+        const QImage radio = indicatorPixels<QRadioButton>(canon, checked);
+        QVERIFY(!radio.isNull());
+        QCOMPARE(radio, indicatorPixels<QRadioButton>(indicators, checked));
+    }
+}
+
 void ModemChromeTest::compactIsSmallerButNotADifferentPalette()
 {
     const QString dialog = ModemChrome::styleSheet(ModemChrome::Scale::Dialog);