diff --git a/crates/mdbook-core/src/book.rs b/crates/mdbook-core/src/book.rs
index 0f8048bc..040612df 100644
--- a/crates/mdbook-core/src/book.rs
+++ b/crates/mdbook-core/src/book.rs
@@ -180,7 +180,14 @@ impl Display for Chapter {
 /// A section number like "1.2.3", basically just a newtype'd `Vec<u32>` with
 /// a pretty `Display` impl.
 #[derive(Debug, PartialEq, Clone, Default, Serialize, Deserialize)]
-pub struct SectionNumber(pub Vec<u32>);
+pub struct SectionNumber(Vec<u32>);
+
+impl SectionNumber {
+    /// Creates a new [`SectionNumber`].
+    pub fn new(numbers: impl Into<Vec<u32>>) -> SectionNumber {
+        SectionNumber(numbers.into())
+    }
+}
 
 impl Display for SectionNumber {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
diff --git a/crates/mdbook-driver/src/load.rs b/crates/mdbook-driver/src/load.rs
index 2afedc74..77b1a41c 100644
--- a/crates/mdbook-driver/src/load.rs
+++ b/crates/mdbook-driver/src/load.rs
@@ -194,7 +194,7 @@ And here is some \
             .unwrap();
 
         let mut second = Link::new("Nested Chapter 1", &second_path);
-        second.number = Some(SectionNumber(vec![1, 2]));
+        second.number = Some(SectionNumber::new([1, 2]));
 
         root.nested_items.push(second.clone().into());
         root.nested_items.push(SummaryItem::Separator);
@@ -255,7 +255,7 @@ And here is some \
         let nested = Chapter {
             name: String::from("Nested Chapter 1"),
             content: String::from("Hello World!"),
-            number: Some(SectionNumber(vec![1, 2])),
+            number: Some(SectionNumber::new([1, 2])),
             path: Some(PathBuf::from("second.md")),
             source_path: Some(PathBuf::from("second.md")),
             parent_names: vec![String::from("Chapter 1")],
diff --git a/crates/mdbook-summary/src/lib.rs b/crates/mdbook-summary/src/lib.rs
index f0aad211..f34488b7 100644
--- a/crates/mdbook-summary/src/lib.rs
+++ b/crates/mdbook-summary/src/lib.rs
@@ -536,7 +536,7 @@ impl<'a> SummaryParser<'a> {
                     let mut link = self.parse_link(dest_url.to_string());
 
                     let mut number = parent.clone();
-                    number.0.push(num_existing_items as u32 + 1);
+                    number.push(num_existing_items as u32 + 1);
                     trace!(
                         "Found chapter: {} {} ({})",
                         number,
@@ -602,7 +602,7 @@ fn update_section_numbers(sections: &mut [SummaryItem], level: usize, by: u32) {
     for section in sections {
         if let SummaryItem::Link(ref mut link) = *section {
             if let Some(ref mut number) = link.number {
-                number.0[level] += by;
+                number[level] += by;
             }
 
             update_section_numbers(&mut link.nested_items, level, by);
@@ -779,7 +779,7 @@ mod tests {
         let link = Link {
             name: String::from("First"),
             location: Some(PathBuf::from("./first.md")),
-            number: Some(SectionNumber(vec![1])),
+            number: Some(SectionNumber::new([1])),
             ..Default::default()
         };
         let should_be = vec![SummaryItem::Link(link)];
@@ -800,18 +800,18 @@ mod tests {
             SummaryItem::Link(Link {
                 name: String::from("First"),
                 location: Some(PathBuf::from("./first.md")),
-                number: Some(SectionNumber(vec![1])),
+                number: Some(SectionNumber::new([1])),
                 nested_items: vec![SummaryItem::Link(Link {
                     name: String::from("Nested"),
                     location: Some(PathBuf::from("./nested.md")),
-                    number: Some(SectionNumber(vec![1, 1])),
+                    number: Some(SectionNumber::new([1, 1])),
                     nested_items: Vec::new(),
                 })],
             }),
             SummaryItem::Link(Link {
                 name: String::from("Second"),
                 location: Some(PathBuf::from("./second.md")),
-                number: Some(SectionNumber(vec![2])),
+                number: Some(SectionNumber::new([2])),
                 nested_items: Vec::new(),
             }),
         ];
@@ -832,13 +832,13 @@ mod tests {
             SummaryItem::Link(Link {
                 name: String::from("First"),
                 location: Some(PathBuf::from("./first.md")),
-                number: Some(SectionNumber(vec![1])),
+                number: Some(SectionNumber::new([1])),
                 nested_items: Vec::new(),
             }),
             SummaryItem::Link(Link {
                 name: String::from("Second"),
                 location: Some(PathBuf::from("./second.md")),
-                number: Some(SectionNumber(vec![2])),
+                number: Some(SectionNumber::new([2])),
                 nested_items: Vec::new(),
             }),
         ];
@@ -860,24 +860,24 @@ mod tests {
             SummaryItem::Link(Link {
                 name: String::from("First"),
                 location: Some(PathBuf::from("./first.md")),
-                number: Some(SectionNumber(vec![1])),
+                number: Some(SectionNumber::new([1])),
                 nested_items: Vec::new(),
             }),
             SummaryItem::Link(Link {
                 name: String::from("Second"),
                 location: Some(PathBuf::from("./second.md")),
-                number: Some(SectionNumber(vec![2])),
+                number: Some(SectionNumber::new([2])),
                 nested_items: Vec::new(),
             }),
             SummaryItem::PartTitle(String::from("Title 2")),
             SummaryItem::Link(Link {
                 name: String::from("Third"),
                 location: Some(PathBuf::from("./third.md")),
-                number: Some(SectionNumber(vec![3])),
+                number: Some(SectionNumber::new([3])),
                 nested_items: vec![SummaryItem::Link(Link {
                     name: String::from("Fourth"),
                     location: Some(PathBuf::from("./fourth.md")),
-                    number: Some(SectionNumber(vec![3, 1])),
+                    number: Some(SectionNumber::new([3, 1])),
                     nested_items: Vec::new(),
                 })],
             }),
@@ -900,13 +900,13 @@ mod tests {
             SummaryItem::Link(Link {
                 name: String::from("First"),
                 location: Some(PathBuf::from("./first.md")),
-                number: Some(SectionNumber(vec![1])),
+                number: Some(SectionNumber::new([1])),
                 nested_items: Vec::new(),
             }),
             SummaryItem::Link(Link {
                 name: String::from("Second"),
                 location: Some(PathBuf::from("./second.md")),
-                number: Some(SectionNumber(vec![2])),
+                number: Some(SectionNumber::new([2])),
                 nested_items: Vec::new(),
             }),
         ];
@@ -928,7 +928,7 @@ mod tests {
         let should_be = vec![SummaryItem::Link(Link {
             name: String::from("Empty"),
             location: None,
-            number: Some(SectionNumber(vec![1])),
+            number: Some(SectionNumber::new([1])),
             nested_items: Vec::new(),
         })];
 
@@ -946,21 +946,21 @@ mod tests {
             SummaryItem::Link(Link {
                 name: String::from("First"),
                 location: Some(PathBuf::from("./first.md")),
-                number: Some(SectionNumber(vec![1])),
+                number: Some(SectionNumber::new([1])),
                 nested_items: Vec::new(),
             }),
             SummaryItem::Separator,
             SummaryItem::Link(Link {
                 name: String::from("Second"),
                 location: Some(PathBuf::from("./second.md")),
-                number: Some(SectionNumber(vec![2])),
+                number: Some(SectionNumber::new([2])),
                 nested_items: Vec::new(),
             }),
             SummaryItem::Separator,
             SummaryItem::Link(Link {
                 name: String::from("Third"),
                 location: Some(PathBuf::from("./third.md")),
-                number: Some(SectionNumber(vec![3])),
+                number: Some(SectionNumber::new([3])),
                 nested_items: Vec::new(),
             }),
         ];
@@ -981,7 +981,7 @@ mod tests {
         let should_be = vec![SummaryItem::Link(Link {
             name: String::from("Chapter title"),
             location: Some(PathBuf::from("./chapter.md")),
-            number: Some(SectionNumber(vec![1])),
+            number: Some(SectionNumber::new([1])),
             nested_items: Vec::new(),
         })];
 
@@ -1000,13 +1000,13 @@ mod tests {
             SummaryItem::Link(Link {
                 name: String::from("test1"),
                 location: Some(PathBuf::from("./test link1.md")),
-                number: Some(SectionNumber(vec![1])),
+                number: Some(SectionNumber::new([1])),
                 nested_items: Vec::new(),
             }),
             SummaryItem::Link(Link {
                 name: String::from("test2"),
                 location: Some(PathBuf::from("./test link2.md")),
-                number: Some(SectionNumber(vec![2])),
+                number: Some(SectionNumber::new([2])),
                 nested_items: Vec::new(),
             }),
         ];
@@ -1089,7 +1089,7 @@ mod tests {
             SummaryItem::Link(Link {
                 name: String::from(name),
                 location: Some(PathBuf::from(location)),
-                number: Some(SectionNumber(numbers.to_vec())),
+                number: Some(SectionNumber::new(numbers)),
                 nested_items,
             })
         };