diff --git a/src/__tests__/index.js b/src/__tests__/index.js
index b5e16e4..6a0f1fe 100644
--- a/src/__tests__/index.js
+++ b/src/__tests__/index.js
@@ -263,6 +263,29 @@ describe("Opentracing interface", () => {
         expect(zipkinTracer.recordBinary).toHaveBeenCalledWith("data", "42");
       });
 
+      it("should log all data in string format", () => {
+        const data = { user: "johndoe" };
+        const id = 345;
+        span.log({ event: "data_received", data, id });
+
+        // should do it in a scope
+        expect(zipkinTracer.scoped).toHaveBeenCalled();
+        zipkinTracer.scoped.mock.calls[0][0]();
+
+        expect(zipkinTracer.recordBinary).toHaveBeenCalledWith(
+          "event",
+          "data_received"
+        );
+        expect(zipkinTracer.recordBinary).toHaveBeenCalledWith(
+          "data",
+          JSON.stringify(data)
+        );
+        expect(zipkinTracer.recordBinary).toHaveBeenCalledWith(
+          "id",
+          JSON.stringify(id)
+        );
+      });
+
       it("should use the right id in log", () => {
         const otherSpan = tracer.startSpan("Other Span", {
           kind: "client"
diff --git a/src/index.js b/src/index.js
index aa88880..13dbc1e 100644
--- a/src/index.js
+++ b/src/index.js
@@ -132,7 +132,10 @@ function SpanCreator({ tracer, serviceName, kind }) {
         tracer.setId(this.id);
 
         Object.entries(obj).map(([key, value]) => {
-          tracer.recordBinary(key, value);
+          tracer.recordBinary(
+            key,
+            typeof value !== "string" ? JSON.stringify(value) : value
+          );
         });
       });
     }
@@ -294,6 +297,7 @@ class Tracing {
   }
 }
 
+
 // These values should match https://github.com/opentracing/opentracing-javascript/blob/master/src/constants.ts
 Tracing.FORMAT_TEXT_MAP = FORMAT_TEXT_MAP;
 Tracing.FORMAT_HTTP_HEADERS = FORMAT_HTTP_HEADERS;