diff --git a/src/decoder.rs b/src/decoder.rs
index 132f657..be652ce 100644
--- a/src/decoder.rs
+++ b/src/decoder.rs
@@ -12,8 +12,6 @@ use crate::jsontypes::RawSourceMap;
 use crate::types::{DecodedMap, RawToken, SourceMap, SourceMapIndex, SourceMapSection};
 use crate::vlq::parse_vlq_segment_into;
 
-const DATA_PREAMBLE: &str = "data:application/json;base64,";
-
 #[derive(PartialEq, Eq)]
 enum HeaderState {
     Undecided,
@@ -339,12 +337,22 @@ pub fn decode_slice(slice: &[u8]) -> Result<DecodedMap> {
     decode_common(rsm)
 }
 
-/// Loads a sourcemap from a data URL
+/// Loads a sourcemap from a data URL.
+///
+/// The URL should match the regex
+/// `data:application/json;(charset=utf-?8;)?base64,(?<base64sourcemap>.+)`.
 pub fn decode_data_url(url: &str) -> Result<DecodedMap> {
-    if !url.starts_with(DATA_PREAMBLE) {
-        return Err(Error::InvalidDataUrl);
-    }
-    let data_b64 = &url[DATA_PREAMBLE.len()..];
+    let rest = url
+        .strip_prefix("data:application/json")
+        .ok_or(Error::InvalidDataUrl)?;
+    let rest = match rest.strip_prefix(";charset=") {
+        Some(rest) => rest
+            .strip_prefix("utf-8")
+            .or_else(|| rest.strip_prefix("utf8"))
+            .ok_or(Error::InvalidDataUrl)?,
+        None => rest,
+    };
+    let data_b64 = rest.strip_prefix(";base64,").ok_or(Error::InvalidDataUrl)?;
     let data = data_encoding::BASE64
         .decode(data_b64.as_bytes())
         .map_err(|_| Error::InvalidDataUrl)?;
diff --git a/tests/test_decoder.rs b/tests/test_decoder.rs
index 9f89802..beaed42 100644
--- a/tests/test_decoder.rs
+++ b/tests/test_decoder.rs
@@ -116,11 +116,11 @@ fn test_basic_sourcemap_source_root_logic() {
 
 #[test]
 fn test_sourcemap_data_url() {
-    let url = "data:application/json;base64,\
+    let base64 = "\
                eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbImNvb2xzdHVmZi5qcyJdLCJzb3VyY2VSb290I\
                joieCIsIm5hbWVzIjpbIngiLCJhbGVydCJdLCJtYXBwaW5ncyI6IkFBQUEsR0FBSUEsR0\
                FBSSxFQUNSLElBQUlBLEdBQUssRUFBRyxDQUNWQyxNQUFNIn0=";
-    match decode_data_url(url).unwrap() {
+    let test_url = |prefix: &str| match decode_data_url(&[prefix, base64].concat()).unwrap() {
         DecodedMap::Regular(sm) => {
             let mut iter = sm.tokens().filter(Token::has_name);
             assert_eq!(
@@ -140,7 +140,10 @@ fn test_sourcemap_data_url() {
         _ => {
             panic!("did not get sourcemap");
         }
-    }
+    };
+    test_url("data:application/json;base64,");
+    test_url("data:application/json;charset=utf-8;base64,");
+    test_url("data:application/json;charset=utf8;base64,");
 }
 
 #[test]