diff --git a/compiler-core/src/javascript/tests/snapshots/gleam_core__javascript__tests__strings__disjoint_string_prefixes_with_guard.snap b/compiler-core/src/javascript/tests/snapshots/gleam_core__javascript__tests__strings__disjoint_string_prefixes_with_guard.snap
new file mode 100644
index 000000000..737d0b1a0
--- /dev/null
+++ b/compiler-core/src/javascript/tests/snapshots/gleam_core__javascript__tests__strings__disjoint_string_prefixes_with_guard.snap
@@ -0,0 +1,30 @@
+---
+source: compiler-core/src/javascript/tests/strings.rs
+expression: "\npub fn classify(input: String) -> String {\n  case input {\n    \"aa\" <> rest if rest == \"x\" -> rest\n    \"b\" <> _ -> \"b-start\"\n    _ -> \"other\"\n  }\n}\n"
+---
+----- SOURCE CODE
+
+pub fn classify(input: String) -> String {
+  case input {
+    "aa" <> rest if rest == "x" -> rest
+    "b" <> _ -> "b-start"
+    _ -> "other"
+  }
+}
+
+
+----- COMPILED JAVASCRIPT
+export function classify(input) {
+  if (input.startsWith("aa")) {
+    let rest = input.slice(2);
+    if (rest === "x") {
+      return rest;
+    } else {
+      return "other";
+    }
+  } else if (input.charCodeAt(0) === 98) {
+    return "b-start";
+  } else {
+    return "other";
+  }
+}
diff --git a/compiler-core/src/javascript/tests/strings.rs b/compiler-core/src/javascript/tests/strings.rs
index 873495abf..28323dbdc 100644
--- a/compiler-core/src/javascript/tests/strings.rs
+++ b/compiler-core/src/javascript/tests/strings.rs
@@ -420,3 +420,19 @@ pub fn classify(input: String) -> String {
 "#,
     );
 }
+
+// https://github.com/gleam-lang/gleam/issues/5856
+#[test]
+fn disjoint_string_prefixes_with_guard() {
+    assert_js!(
+        r#"
+pub fn classify(input: String) -> String {
+  case input {
+    "aa" <> rest if rest == "x" -> rest
+    "b" <> _ -> "b-start"
+    _ -> "other"
+  }
+}
+"#,
+    );
+}
diff --git a/test/language/test/language/string_pattern_matching_test.gleam b/test/language/test/language/string_pattern_matching_test.gleam
index 3e88523de..098c8a9d3 100644
--- a/test/language/test/language/string_pattern_matching_test.gleam
+++ b/test/language/test/language/string_pattern_matching_test.gleam
@@ -244,3 +244,19 @@ pub fn string_prefix_multibyte_falls_through_to_shorter_test() {
   assert classify("🫥z") == "z"
   assert classify("abc") == "other"
 }
+
+// https://github.com/gleam-lang/gleam/issues/5856
+pub fn disjoint_string_prefixes_with_guard_test() {
+  let classify = fn(input: String) -> String {
+    case input {
+      "aa" <> rest if rest == "x" -> rest
+      "b" <> _ -> "b-start"
+      _ -> "other"
+    }
+  }
+
+  assert classify("aax") == "x"
+  assert classify("aay") == "other"
+  assert classify("bcd") == "b-start"
+  assert classify("zzz") == "other"
+}