diff --git a/package-lock.json b/package-lock.json
--- a/package-lock.json
+++ b/package-lock.json
@@ -90,7 +90,7 @@
     },
     "duplexer": {
       "version": "0.1.1",
-      "resolved": "http://registry.npmjs.org/duplexer/-/duplexer-0.1.1.tgz",
+      "resolved": "https://registry.npmjs.org/duplexer/-/duplexer-0.1.1.tgz",
       "integrity": "sha1-rOb/gIwc5mtX0ev5eXessCM0z8E=",
       "dev": true
     },
@@ -144,7 +144,7 @@
       "dependencies": {
         "tape": {
           "version": "2.3.3",
-          "resolved": "http://registry.npmjs.org/tape/-/tape-2.3.3.tgz",
+          "resolved": "https://registry.npmjs.org/tape/-/tape-2.3.3.tgz",
           "integrity": "sha1-Lnzgox3wn41oUWZKcYQuDKUFevc=",
           "dev": true,
           "requires": {
@@ -277,7 +277,7 @@
     },
     "minimist": {
       "version": "0.0.5",
-      "resolved": "http://registry.npmjs.org/minimist/-/minimist-0.0.5.tgz",
+      "resolved": "https://registry.npmjs.org/minimist/-/minimist-0.0.5.tgz",
       "integrity": "sha1-16oye87PUY+RBqxrjwA/o7zqhWY=",
       "dev": true
     },
@@ -316,7 +316,7 @@
     },
     "readable-stream": {
       "version": "1.1.14",
-      "resolved": "http://registry.npmjs.org/readable-stream/-/readable-stream-1.1.14.tgz",
+      "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-1.1.14.tgz",
       "integrity": "sha1-fPTFTvZI44EwhMY23SB54WbAgdk=",
       "dev": true,
       "requires": {
@@ -369,7 +369,7 @@
     },
     "string_decoder": {
       "version": "0.10.31",
-      "resolved": "http://registry.npmjs.org/string_decoder/-/string_decoder-0.10.31.tgz",
+      "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-0.10.31.tgz",
       "integrity": "sha1-YuIDvEF2bGwoyfyEMB2rHFMQ+pQ=",
       "dev": true
     },
@@ -432,7 +432,7 @@
     },
     "through2": {
       "version": "0.2.3",
-      "resolved": "http://registry.npmjs.org/through2/-/through2-0.2.3.tgz",
+      "resolved": "https://registry.npmjs.org/through2/-/through2-0.2.3.tgz",
       "integrity": "sha1-6zKE2k6jEbbMis42U3SKUqvyWj8=",
       "dev": true,
       "requires": {
diff --git a/src/main/ts/log/ConsoleWriter.ts b/src/main/ts/log/ConsoleWriter.ts
--- a/src/main/ts/log/ConsoleWriter.ts
+++ b/src/main/ts/log/ConsoleWriter.ts
@@ -95,6 +95,6 @@ export class ConsoleWriter extends TextW
         if (isNullOrEmptyString(spec))
             this._buffer.push(value);
         else
-            super.writeValue(value);
+            super.writeValue(value, spec);
     }
 }
diff --git a/src/test/ts/TraceSourceTests.ts b/src/test/ts/TraceSourceTests.ts
--- a/src/test/ts/TraceSourceTests.ts
+++ b/src/test/ts/TraceSourceTests.ts
@@ -83,4 +83,7 @@ test("console writer", (t, trace) => {
 
     trace.log({ foo: "bar" });
     t.deepEqual(mockConsole.getLine(1), ["console writer: ", { foo: "bar" }], "Log an object");
+
+    trace.log("json: {0:json}", { foo: "bar" });
+    t.deepEqual(mockConsole.getLine(2), ['console writer: json: {\n  "foo": "bar"\n}'], "should convert to string substitutions with spec");
 });