2 files changed, 23 insertions, 1 deletions
diff --git a/ui/app/conversion-util.js b/ui/app/conversion-util.js
index 337763067..a7a226cc5 100644
--- a/ui/app/conversion-util.js
+++ b/ui/app/conversion-util.js
@@ -140,7 +140,7 @@ const addCurrencies = (a, b, options = {}) => {
     bBase,
     ...conversionOptions
   } = options
-  const value = (new BigNumber(a, aBase)).add(b, bBase)
+  const value = (new BigNumber(a.toString(), aBase)).add(b.toString(), bBase)
 
   return converter({
     value,
diff --git a/ui/app/conversion-util.test.js b/ui/app/conversion-util.test.js
new file mode 100644
index 000000000..368ce3bba
--- /dev/null
+++ b/ui/app/conversion-util.test.js
@@ -0,0 +1,22 @@
+import assert from 'assert'
+import {addCurrencies} from './conversion-util'
+
+
+describe('conversion utils', () => {
+  describe('addCurrencies()', () => {
+    it('add whole numbers', () => {
+      const result = addCurrencies(3, 9)
+      assert.equal(result.toNumber(), 12)
+    })
+
+    it('add decimals', () => {
+      const result = addCurrencies(1.3, 1.9)
+      assert.equal(result.toNumber(), 3.2)
+    })
+
+    it('add repeating decimals', () => {
+      const result = addCurrencies(1 / 3, 1 / 9)
+      assert.equal(result.toNumber(), 0.4444444444444444)
+    })
+  })
+})