diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 397ae1791a8..77fbc7902c8 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -604,6 +604,17 @@ module ts {
                 };
 
                 function serializeSourceMapContents(version: number, file: string, sourceRoot: string, sources: string[], names: string[], mappings: string) {
+                    if (typeof JSON !== "undefined") {
+                        return JSON.stringify({
+                            version: version,
+                            file: file,
+                            sourceRoot: sourceRoot,
+                            sources: sources,
+                            names: names,
+                            mappings: mappings
+                        });
+                    }
+
                     return "{\"version\":" + version + ",\"file\":\"" + escapeString(file) + "\",\"sourceRoot\":\"" + escapeString(sourceRoot) + "\",\"sources\":[" + serializeStringArray(sources) + "],\"names\":[" + serializeStringArray(names) + "],\"mappings\":\"" + escapeString(mappings) + "\"}";
 
                     /** This does not support the full escape characters, it only supports the subset that can be used in file names