diff --git a/core/src/main/java/org/bitcoinj/utils/ExchangeRate.java b/core/src/main/java/org/bitcoinj/utils/ExchangeRate.java
index 10c928e6..d3b8468d 100644
--- a/core/src/main/java/org/bitcoinj/utils/ExchangeRate.java
+++ b/core/src/main/java/org/bitcoinj/utils/ExchangeRate.java
@@ -70,6 +70,10 @@ public class ExchangeRate implements Serializable {
         if (converted.compareTo(BigInteger.valueOf(Long.MAX_VALUE)) > 0
                 || converted.compareTo(BigInteger.valueOf(Long.MIN_VALUE)) < 0)
             throw new ArithmeticException("Overflow");
-        return Coin.valueOf(converted.longValue());
+        try {
+            return Coin.valueOf(converted.longValue());
+        } catch (IllegalArgumentException x) {
+            throw new ArithmeticException("Overflow: " + x.getMessage());
+        }
     }
 }
diff --git a/core/src/test/java/org/bitcoinj/utils/ExchangeRateTest.java b/core/src/test/java/org/bitcoinj/utils/ExchangeRateTest.java
index c31a28d1..8c8f2b0f 100644
--- a/core/src/test/java/org/bitcoinj/utils/ExchangeRateTest.java
+++ b/core/src/test/java/org/bitcoinj/utils/ExchangeRateTest.java
@@ -50,4 +50,28 @@ public class ExchangeRateTest {
         ExchangeRate rate = new ExchangeRate(Fiat.parseFiat("EUR", "500"));
         rate.fiatToCoin(Fiat.parseFiat("USD", "1"));
     }
+
+    @Test(expected = ArithmeticException.class)
+    public void fiatToCoinTooLarge() throws Exception {
+        ExchangeRate rate = new ExchangeRate(Fiat.parseFiat("XXX", "1"));
+        rate.fiatToCoin(Fiat.parseFiat("XXX", "21000001"));
+    }
+
+    @Test(expected = ArithmeticException.class)
+    public void fiatToCoinTooSmall() throws Exception {
+        ExchangeRate rate = new ExchangeRate(Fiat.parseFiat("XXX", "1"));
+        rate.fiatToCoin(Fiat.parseFiat("XXX", "-21000001"));
+    }
+
+    @Test(expected = ArithmeticException.class)
+    public void coinToFiatTooLarge() throws Exception {
+        ExchangeRate rate = new ExchangeRate(Fiat.parseFiat("XXX", "1000000000"));
+        rate.coinToFiat(Coin.parseCoin("1000000"));
+    }
+
+    @Test(expected = ArithmeticException.class)
+    public void coinToFiatTooSmall() throws Exception {
+        ExchangeRate rate = new ExchangeRate(Fiat.parseFiat("XXX", "1000000000"));
+        rate.coinToFiat(Coin.parseCoin("-1000000"));
+    }
 }