diff --git a/packages/util/src/format/formatBalance.spec.ts b/packages/util/src/format/formatBalance.spec.ts
index 14a0a3dcb..e5da0c4e7 100644
--- a/packages/util/src/format/formatBalance.spec.ts
+++ b/packages/util/src/format/formatBalance.spec.ts
@@ -9,6 +9,12 @@ import formatBalance from './formatBalance';
 describe('formatBalance', () => {
   const TESTVAL = new BN('123456789000');
 
+  it('does not allow float inputs', () => {
+    expect(
+      () => formatBalance(0.01234)
+    ).toThrow(/integer input value/);
+  });
+
   it('formats empty to 0', () => {
     expect(formatBalance()).toEqual('0');
     expect(formatBalance('0')).toEqual('0');
diff --git a/packages/util/src/format/formatBalance.ts b/packages/util/src/format/formatBalance.ts
index 7b4b4d497..ad0613d13 100644
--- a/packages/util/src/format/formatBalance.ts
+++ b/packages/util/src/format/formatBalance.ts
@@ -4,9 +4,10 @@
 
 import BN from 'bn.js';
 
+import assert from '../assert';
 import isUndefined from '../is/undefined';
-import { SI, SI_MID, SiDef, calcSi, findSi } from './si';
 import formatDecimal from './formatDecimal';
+import { SI, SI_MID, SiDef, calcSi, findSi } from './si';
 
 type Defaults = {
   decimals: number,
@@ -36,6 +37,8 @@ function _formatBalance (input?: number | string | BN, withSi: boolean = true, d
     return '0';
   }
 
+  assert(/^\d+$/.test(text), `Non-integer input value '${text}' supplied to balanceFormat`);
+
   // NOTE We start at midpoint (8) minus 1 - this means that values display as
   // 123.456 instead of 0.123k (so always 6 relevant). Additionally we us ceil
   // so there are at most 3 decimal before the decimal seperator