2 files changed, 25 insertions, 5 deletions
diff --git a/src/bun.js/javascript.zig b/src/bun.js/javascript.zig
index 492b9fbee..062bd52a2 100644
--- a/src/bun.js/javascript.zig
+++ b/src/bun.js/javascript.zig
@@ -113,6 +113,8 @@ const ParsedSourceMap = SourceMap.Mapping.ParsedSourceMap;
 const MappingList = SourceMap.Mapping.List;
 
 pub const SavedSourceMap = struct {
+    pub const vlq_offset = 24;
+
     // For bun.js, we store the number of mappings and how many bytes the final list is at the beginning of the array
     // The first 8 bytes are the length of the array
     // The second 8 bytes are the number of mappings
@@ -120,7 +122,7 @@ pub const SavedSourceMap = struct {
         data: [*]u8,
 
         pub fn vlq(this: SavedMappings) []u8 {
-            return this.data[24..this.len()];
+            return this.data[vlq_offset..this.len()];
         }
 
         pub inline fn len(this: SavedMappings) usize {
@@ -134,7 +136,7 @@ pub const SavedSourceMap = struct {
         pub fn toMapping(this: SavedMappings, allocator: Allocator, path: string) anyerror!ParsedSourceMap {
             const result = SourceMap.Mapping.parse(
                 allocator,
-                this.data[24..this.len()],
+                this.data[vlq_offset..this.len()],
                 @as(usize, @bitCast(this.data[8..16].*)),
                 1,
                 @as(usize, @bitCast(this.data[16..24].*)),
@@ -527,7 +529,7 @@ pub const VirtualMachine = struct {
         pub fn onChunk(this: *SourceMapHandlerGetter, chunk: SourceMap.Chunk, source: logger.Source) anyerror!void {
             var temp_json_buffer = bun.MutableString.initEmpty(bun.default_allocator);
             defer temp_json_buffer.deinit();
-            temp_json_buffer = try chunk.printSourceMapContents(source, temp_json_buffer, true, true);
+            temp_json_buffer = try chunk.printSourceMapContentsAtOffset(source, temp_json_buffer, true, SavedSourceMap.vlq_offset, true);
             const source_map_url_prefix_start = "//# sourceMappingURL=data:application/json;base64,";
             // TODO: do we need to %-encode the path?
             const source_url_len = source.path.text.len;
diff --git a/src/sourcemap/sourcemap.zig b/src/sourcemap/sourcemap.zig
index 0bcb4021d..411e8523d 100644
--- a/src/sourcemap/sourcemap.zig
+++ b/src/sourcemap/sourcemap.zig
@@ -1122,6 +1122,24 @@ pub const Chunk = struct {
         include_sources_contents: bool,
         comptime ascii_only: bool,
     ) !MutableString {
+        return printSourceMapContentsAtOffset(
+            chunk,
+            source,
+            mutable,
+            include_sources_contents,
+            0,
+            ascii_only,
+        );
+    }
+
+    pub fn printSourceMapContentsAtOffset(
+        chunk: Chunk,
+        source: Logger.Source,
+        mutable: MutableString,
+        include_sources_contents: bool,
+        offset: usize,
+        comptime ascii_only: bool,
+    ) !MutableString {
         var output = mutable;
 
         // attempt to pre-allocate
@@ -1137,7 +1155,7 @@ pub const Chunk = struct {
         }
 
         output.growIfNeeded(
-            filename.len + 2 + (source.contents.len * @as(usize, @intFromBool(include_sources_contents))) + chunk.buffer.list.items.len + 32 + 39 + 29 + 22 + 20,
+            filename.len + 2 + (source.contents.len * @as(usize, @intFromBool(include_sources_contents))) + (chunk.buffer.list.items.len - offset) + 32 + 39 + 29 + 22 + 20,
         ) catch unreachable;
         try output.append("{\n  \"version\":3,\n  \"sources\": [");
 
@@ -1149,7 +1167,7 @@ pub const Chunk = struct {
         }
 
         try output.append("],\n  \"mappings\": ");
-        output = try JSPrinter.quoteForJSON(chunk.buffer.list.items, output, ascii_only);
+        output = try JSPrinter.quoteForJSON(chunk.buffer.list.items[offset..], output, ascii_only);
         try output.append(", \"names\": []\n}");
 
         return output;