diff --git a/src/Integrations/Divi/Design/DiviThemeOptionsGetAbility.php b/src/Integrations/Divi/Design/DiviThemeOptionsGetAbility.php
index 386b263..c3d137b 100644
--- a/src/Integrations/Divi/Design/DiviThemeOptionsGetAbility.php
+++ b/src/Integrations/Divi/Design/DiviThemeOptionsGetAbility.php
@@ -122,7 +122,8 @@ final class DiviThemeOptionsGetAbility implements Ability, RequiresDiviFeatures
             return $keys;
         }
 
-        $book = ThemeOptionBook::fromDivi($this->options->read());
+        $stored = ThemeOptionBook::fromDivi($this->options->read());
+        $book = $stored->withoutFalse();
         $rows = [];
         foreach ($keys as $key) {
             $definition = ThemeOptionSpec::definition($key);
@@ -137,7 +138,7 @@ final class DiviThemeOptionsGetAbility implements Ability, RequiresDiviFeatures
             ] + array_intersect_key($definition, array_flip(self::RULES));
         }
 
-        return ['options' => $rows, 'design_rev' => $book->rev(), 'notes' => self::NOTES];
+        return ['options' => $rows, 'design_rev' => $stored->rev(), 'notes' => self::NOTES];
     }
 
     /** Like lit/divi-design-system: whoever edits content may read the design. */
diff --git a/src/Integrations/Divi/Design/DiviThemeOptionsUpdateAbility.php b/src/Integrations/Divi/Design/DiviThemeOptionsUpdateAbility.php
index 1e004f2..ffebb23 100644
--- a/src/Integrations/Divi/Design/DiviThemeOptionsUpdateAbility.php
+++ b/src/Integrations/Divi/Design/DiviThemeOptionsUpdateAbility.php
@@ -123,7 +123,7 @@ final class DiviThemeOptionsUpdateAbility implements Ability, RequiresDiviFeatur
             $this->name(),
             new ThemeOptionsArea($this->options),
             $input,
-            fn (array $raw): DesignPlan|WP_Error => $this->plan(ThemeOptionBook::fromDivi($raw), $set)
+            fn (array $raw): DesignPlan|WP_Error => $this->plan(ThemeOptionBook::fromDivi($raw)->withoutFalse(), $set)
         );
     }
 
diff --git a/src/Integrations/Divi/Design/ThemeOptionBook.php b/src/Integrations/Divi/Design/ThemeOptionBook.php
index 32d2c26..da23463 100644
--- a/src/Integrations/Divi/Design/ThemeOptionBook.php
+++ b/src/Integrations/Divi/Design/ThemeOptionBook.php
@@ -77,4 +77,10 @@ final class ThemeOptionBook
     {
         return self::fromDivi(array_diff_key($this->data, [$key => true]));
     }
+
+    /** Divi stores its default font as false: that is "not set" (W3), as ThemeOptionSpec::effective() sees it. */
+    public function withoutFalse(): self
+    {
+        return self::fromDivi(array_filter($this->data, static fn (mixed $value): bool => $value !== false));
+    }
 }
diff --git a/tests/Unit/Integrations/Divi/Design/DiviThemeOptionsGetAbilityTest.php b/tests/Unit/Integrations/Divi/Design/DiviThemeOptionsGetAbilityTest.php
index e357a75..93e5acf 100644
--- a/tests/Unit/Integrations/Divi/Design/DiviThemeOptionsGetAbilityTest.php
+++ b/tests/Unit/Integrations/Divi/Design/DiviThemeOptionsGetAbilityTest.php
@@ -84,6 +84,23 @@ final class DiviThemeOptionsGetAbilityTest extends TestCase
         self::assertSame('Open Sans', $rows['body_font']['value']);
     }
 
+    /** Divi stores its default font as false: reported as not set, with the default in effect. */
+    public function testAStoredFalseCountsAsNotSet(): void
+    {
+        $stored = ['heading_font' => false] + ThemeOptionsAreaTest::stored();
+        $writes = [];
+        $ability = new DiviThemeOptionsGetAbility(ThemeOptionsAreaTest::adapter($stored, $writes));
+
+        $result = $ability->execute([]);
+        $row = self::byKey($result)['heading_font'];
+        self::assertSame(ThemeOptionBook::fromDivi($stored)->rev(), $result['design_rev'], 'the rev of the dry run');
+
+        self::assertNull($row['value']);
+        self::assertTrue($row['is_default']);
+        self::assertSame(ThemeOptionSpec::effective('heading_font', []), $row['effective']);
+        self::assertSame($row['effective'], $row['default']);
+    }
+
     /** Ruling W3: an unset tablet size inherits the desktop size – as effective value and as its default. */
     public function testUnsetSizesInheritTheLargerSize(): void
     {
diff --git a/tests/Unit/Integrations/Divi/Design/DiviThemeOptionsUpdateAbilityTest.php b/tests/Unit/Integrations/Divi/Design/DiviThemeOptionsUpdateAbilityTest.php
index f3ffbaf..fef9be7 100644
--- a/tests/Unit/Integrations/Divi/Design/DiviThemeOptionsUpdateAbilityTest.php
+++ b/tests/Unit/Integrations/Divi/Design/DiviThemeOptionsUpdateAbilityTest.php
@@ -280,6 +280,22 @@ final class DiviThemeOptionsUpdateAbilityTest extends TestCase
         self::assertSame([], $this->writes);
     }
 
+    /** A stored false (Divi's default font) is "not set": null is no change, a font is "added". */
+    public function testAStoredFalseCountsAsNotSet(): void
+    {
+        $this->stored = ['heading_font' => false] + $this->stored;
+
+        self::assertSame([], $this->ability()->execute(['set' => ['heading_font' => null]])['diff']);
+        $dry = self::assertToolError(
+            $this->ability()->execute(['set' => ['heading_font' => 'Roboto']]),
+            'confirm_required'
+        );
+        self::assertSame([['heading_font', 'added']], array_map(
+            static fn (array $row): array => [$row['key'], $row['action']],
+            $dry['diff']
+        ));
+    }
+
     public function testUnchangedValuesAreNoChange(): void
     {
         $result = $this->ability()->execute(['set' => ['body_font_size' => 16, 'gutter_width' => null]]);