diff --git a/rust/rubydex/src/indexing/rbs_indexer.rs b/rust/rubydex/src/indexing/rbs_indexer.rs
index 239934af..b5823a3d 100644
--- a/rust/rubydex/src/indexing/rbs_indexer.rs
+++ b/rust/rubydex/src/indexing/rbs_indexer.rs
@@ -271,14 +271,16 @@ impl<'a> RBSIndexer<'a> {
 
         for (key, _value) in function_node.required_keywords().iter() {
             let name = self.source_at(&key.location());
-            let offset = Offset::from_rbs_location(&key.location());
+            // Extend offset by 1 to include the trailing colon, matching Ruby indexer behavior
+            let offset = Offset::from_rbs_location(&key.location()).extend_end(1);
             let str_id = self.local_graph.intern_string(name);
             parameters.push(Parameter::RequiredKeyword(ParameterStruct::new(offset, str_id)));
         }
 
         for (key, _value) in function_node.optional_keywords().iter() {
             let name = self.source_at(&key.location());
-            let offset = Offset::from_rbs_location(&key.location());
+            // Extend offset by 1 to include the trailing colon, matching Ruby indexer behavior
+            let offset = Offset::from_rbs_location(&key.location()).extend_end(1);
             let str_id = self.local_graph.intern_string(name);
             parameters.push(Parameter::OptionalKeyword(ParameterStruct::new(offset, str_id)));
         }
@@ -1257,12 +1259,12 @@ mod tests {
 
             assert_parameter!(&def.signatures().as_slice()[0][4], RequiredKeyword, |param| {
                 assert_string_eq!(context, param.str(), "name");
-                assert_offset_string!(context, param.offset(), "name");
+                assert_offset_string!(context, param.offset(), "name:");
             });
 
             assert_parameter!(&def.signatures().as_slice()[0][5], OptionalKeyword, |param| {
                 assert_string_eq!(context, param.str(), "age");
-                assert_offset_string!(context, param.offset(), "age");
+                assert_offset_string!(context, param.offset(), "age:");
             });
 
             assert_parameter!(&def.signatures().as_slice()[0][6], RestKeyword, |param| {
@@ -1298,12 +1300,12 @@ mod tests {
 
             assert_parameter!(&def.signatures().as_slice()[0][4], RequiredKeyword, |param| {
                 assert_string_eq!(context, param.str(), "name");
-                assert_offset_string!(context, param.offset(), "name");
+                assert_offset_string!(context, param.offset(), "name:");
             });
 
             assert_parameter!(&def.signatures().as_slice()[0][5], OptionalKeyword, |param| {
                 assert_string_eq!(context, param.str(), "age");
-                assert_offset_string!(context, param.offset(), "age");
+                assert_offset_string!(context, param.offset(), "age:");
             });
 
             assert_parameter!(&def.signatures().as_slice()[0][6], RestKeyword, |param| {
diff --git a/rust/rubydex/src/offset.rs b/rust/rubydex/src/offset.rs
index 7bef5199..efdff4ca 100644
--- a/rust/rubydex/src/offset.rs
+++ b/rust/rubydex/src/offset.rs
@@ -74,6 +74,15 @@ impl Offset {
         self.end
     }
 
+    /// Returns a new offset with the end extended by the given number of bytes.
+    #[must_use]
+    pub const fn extend_end(self, bytes: u32) -> Self {
+        Self {
+            start: self.start,
+            end: self.end + bytes,
+        }
+    }
+
     /// Converts an offset to a display range like `1:1-1:5`
     #[must_use]
     pub fn to_display_range(&self, document: &Document) -> String {