diff --git a/inputs/passing/stringMethods/lastIndexOf.ts b/inputs/passing/stringMethods/lastIndexOf.ts
new file mode 100644
index 0000000..2f4088c
--- /dev/null
+++ b/inputs/passing/stringMethods/lastIndexOf.ts
@@ -0,0 +1,17 @@
+// test_output! [[4,2,4,6],[-1,-1]]
+
+export default function () {
+  const positive = [
+    "  xxx".lastIndexOf("x"),
+    "xxx  ".lastIndexOf("x"),
+    "  xxx  ".lastIndexOf("x"),
+    "  xyxyxy  ".lastIndexOf("xy"),
+  ];
+
+  const negative = [
+    "  xxx  ".lastIndexOf("x", 5),
+    "abc".lastIndexOf("abcd"),
+  ];
+
+  return [positive, negative];
+}
diff --git a/valuescript_vm/src/string_methods.rs b/valuescript_vm/src/string_methods.rs
index 3f2f645..f6a2b3d 100644
--- a/valuescript_vm/src/string_methods.rs
+++ b/valuescript_vm/src/string_methods.rs
@@ -49,6 +49,7 @@ pub fn get_string_method(method: &str) -> Val {
     "endsWith" => Val::Static(&ENDS_WITH),
     "includes" => Val::Static(&INCLUDES),
     "indexOf" => Val::Static(&INDEX_OF),
+    "lastIndexOf" => Val::Static(&LAST_INDEX_OF),
     _ => Val::Undefined,
   }
 }
@@ -222,6 +223,38 @@ static INDEX_OF: NativeFunction = NativeFunction {
   },
 };
 
+static LAST_INDEX_OF: NativeFunction = NativeFunction {
+  fn_: |this: &mut Val, params: Vec<Val>| -> Val {
+    match this {
+      Val::String(string_data) => {
+        let string_bytes = string_data.as_bytes();
+
+        let search_string = match params.get(0) {
+          Some(s) => s.val_to_string(),
+          _ => return Val::Number(-1.0),
+        };
+
+        let search_bytes = search_string.as_bytes();
+
+        let at_least_pos = match params.get(1) {
+          Some(p) => match p.to_index() {
+            // FIXME: to_index isn't quite right here
+            Some(i) => i,
+            None => return Val::Number(-1.0),
+          },
+          _ => 0,
+        };
+
+        match last_index_of(string_bytes, search_bytes, at_least_pos) {
+          Some(i) => Val::Number(i as f64),
+          None => Val::Number(-1.0),
+        }
+      }
+      _ => std::panic!("Not implemented: exceptions/string indirection"),
+    }
+  },
+};
+
 fn index_of(string_bytes: &[u8], search_bytes: &[u8], start_pos: usize) -> Option<usize> {
   let search_length = search_bytes.len();
 
@@ -235,19 +268,38 @@ fn index_of(string_bytes: &[u8], search_bytes: &[u8], start_pos: usize) -> Optio
     return Some(0);
   }
 
-  for i in start_pos..(string_bytes.len() - search_length + 1) {
-    let mut found = true;
-
+  'outer: for i in start_pos..=(string_bytes.len() - search_length) {
     for j in 0..search_length {
       if string_bytes[i + j] != search_bytes[j] {
-        found = false;
-        break;
+        continue 'outer;
       }
     }
 
-    if found {
-      return Some(i);
+    return Some(i);
+  }
+
+  None
+}
+
+fn last_index_of(string_bytes: &[u8], search_bytes: &[u8], at_least_pos: usize) -> Option<usize> {
+  let search_length = search_bytes.len();
+
+  if search_length > string_bytes.len() {
+    return None;
+  }
+
+  if search_length == 0 {
+    return Some(string_bytes.len());
+  }
+
+  'outer: for i in (at_least_pos..=string_bytes.len() - search_length).rev() {
+    for j in 0..search_length {
+      if string_bytes[i + j] != search_bytes[j] {
+        continue 'outer;
+      }
     }
+
+    return Some(i);
   }
 
   None