diff --git a/CHANGELOG-rust.md b/CHANGELOG-rust.md
index a7c6eb30..88829517 100644
--- a/CHANGELOG-rust.md
+++ b/CHANGELOG-rust.md
@@ -5,6 +5,10 @@ This changelog tracks the Rust `svdtools` project. See
 
 ## [Unreleased]
 
+## [v0.3.17] 2024-07-05
+
+* Support "isDefault" enum value in `svdtools html`
+
 ## [v0.3.16] 2024-07-03
 
 * Add possibility to add field arrays
@@ -171,7 +175,8 @@ Other changes:
 
 * Initial release with feature-parity with the Python project.
 
-[Unreleased]: https://github.com/rust-embedded/svdtools/compare/v0.3.16...HEAD
+[Unreleased]: https://github.com/rust-embedded/svdtools/compare/v0.3.17...HEAD
+[v0.3.17]: https://github.com/rust-embedded/svdtools/compare/v0.3.16...v0.3.17
 [v0.3.16]: https://github.com/rust-embedded/svdtools/compare/v0.3.15...v0.3.16
 [v0.3.15]: https://github.com/rust-embedded/svdtools/compare/v0.3.14...v0.3.15
 [v0.3.14]: https://github.com/rust-embedded/svdtools/compare/v0.3.13...v0.3.14
diff --git a/Cargo.toml b/Cargo.toml
index 639534be..63372e43 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "svdtools"
-version = "0.3.16"
+version = "0.3.17"
 repository = "https://github.com/rust-embedded/svdtools/"
 description = "Tool for modifying bugs in CMSIS SVD"
 authors = [
diff --git a/src/html/html_cli.rs b/src/html/html_cli.rs
index e35e5741..159b44aa 100644
--- a/src/html/html_cli.rs
+++ b/src/html/html_cli.rs
@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::collections::BTreeMap;
 use std::fs::File;
 use std::io::{Read, Write};
 #[cfg(target_os = "linux")]
@@ -23,6 +24,7 @@ use svd_parser::{
     expand::{derive_peripheral, Index},
     svd::{Access, Cluster, Register, RegisterInfo, WriteConstraint},
 };
+use svd_rs::{EnumeratedValue, EnumeratedValues};
 
 fn sanitize(input: &str) -> String {
     use once_cell::sync::Lazy;
@@ -261,9 +263,19 @@ fn parse_register(
                 };
 
                 for value in &enums.values {
+                    let val = if let Some(value) = value.value {
+                        value.to_string()
+                    } else {
+                        let val = value
+                            .is_default()
+                            .then(|| enums_to_map(&enums))
+                            .and_then(|map| minimal_hole(&map, fwidth))
+                            .ok_or_else(|| anyhow!("Value is missing from {value:?}"))?;
+                        format!("{val} (+)")
+                    };
+
                     doc += &format!(
-                        "<strong>{}: {}</strong>: {}<br>",
-                        value.value.unwrap(),
+                        "<strong>{val}: {}</strong>: {}<br>",
                         value.name,
                         sanitize(value.description.as_deref().unwrap_or(""))
                     );
@@ -272,7 +284,7 @@ fn parse_register(
             } else if let Some(WriteConstraint::Range(wcrange)) = wc.as_ref() {
                 let mn = hex(wcrange.min);
                 let mx = hex(wcrange.max);
-                fdoc = Some(format!("Allowed values: {mn}-{mx}"));
+                fdoc = Some(format!("Allowed values: <strong>{mn}-{mx}</strong>"));
             }
         }
         fields.push(object!({
@@ -514,3 +526,17 @@ pub fn svd2html(htmldir: &Path, svdfiles: &[PathBuf]) -> anyhow::Result<()> {
     generate_index_page(&devices, &mut file)?;
     Ok(())
 }
+
+fn enums_to_map(evs: &EnumeratedValues) -> BTreeMap<u64, &EnumeratedValue> {
+    let mut map = BTreeMap::new();
+    for ev in &evs.values {
+        if let Some(v) = ev.value {
+            map.insert(v, ev);
+        }
+    }
+    map
+}
+
+fn minimal_hole(map: &BTreeMap<u64, &EnumeratedValue>, width: u32) -> Option<u64> {
+    (0..(1u64 << width)).find(|&v| !map.contains_key(&v))
+}