diff --git a/package.json b/package.json
index 3dfc8462..b0fe3e4b 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,7 @@
     "test": "npm run test-unit",
     "test-unit": "mocha --recursive \"./{,!(node_modules)/**/}*.spec.js\" || echo .",
     "start": "echo Run node client.js start [instance] to start slaves && node master.js",
-    "cover": "./node_modules/.bin/istanbul cover ./node_modules/mocha/bin/_mocha -- lib/*.js -R spec"
+    "cover": "./node_modules/.bin/istanbul cover ./node_modules/mocha/bin/_mocha -- \"./{,!(node_modules)/**/}*.spec.js\" -R spec"
   },
   "keywords": [
     "factorio"
diff --git a/sharedPlugins/inventoryImports/isJson.js b/sharedPlugins/inventoryImports/isJson.js
index 6bd89302..597564df 100644
--- a/sharedPlugins/inventoryImports/isJson.js
+++ b/sharedPlugins/inventoryImports/isJson.js
@@ -1,9 +1,11 @@
 module.exports = function(x){
+	if(x === false || x === true || x === null) return true; // === false is valid JSON, so is true and null
 	var isNotJson = false
 	try{
 		z = JSON.parse(x);
 	} catch (e) {
 		isNotJson = true;
 	}
+	
 	return !isNotJson;
 }
\ No newline at end of file
diff --git a/sharedPlugins/inventoryImports/isJson.spec.js b/sharedPlugins/inventoryImports/isJson.spec.js
new file mode 100644
index 00000000..4f76fe48
--- /dev/null
+++ b/sharedPlugins/inventoryImports/isJson.spec.js
@@ -0,0 +1,20 @@
+const isJson = require("./isJson");
+const assert = require("assert");
+
+describe("isJson.js()", function(){
+	it("checks if a thing is valid JSON", function(){
+		assert(isJson("string") === false);
+		assert(isJson("{js_object_notation='very false'}") === false);
+		assert(isJson('{ "name":"John", "age":31, "city":"New York" }') === true);
+	});
+	it("recognizes that true and false are both valid JSON", function(){
+		assert(isJson(true) === true);
+		assert(isJson(false) === true);
+	});
+	it("Handles null as valid JSON (after spec)", function(){
+		assert(isJson(null) === true);
+	});
+	it("Recognizes that JSON doesn't allow trailing commas (,)", function(){
+		assert(isJson('["a", "b", ]') === false);
+	});
+});