diff --git a/CHANGELOG.md b/CHANGELOG.md
index 26adc443..d4f9bde7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,9 +21,11 @@ and this project adheres to
   query ([#1170]).
 - @cosmjs/tendermint-rpc: Fix decoding validator updates due to slashing
   ([#1177]).
+- @cosmjs/math: Check for negative values in `Decimal.fromAtomics` ([#1188]).
 
 [#1170]: https://github.com/cosmos/cosmjs/issues/1170
 [#1177]: https://github.com/cosmos/cosmjs/issues/1177
+[#1188]: https://github.com/cosmos/cosmjs/pull/1188
 
 ### Changed
 
diff --git a/packages/math/src/decimal.spec.ts b/packages/math/src/decimal.spec.ts
index 52b876f7..dcefcad3 100644
--- a/packages/math/src/decimal.spec.ts
+++ b/packages/math/src/decimal.spec.ts
@@ -31,6 +31,18 @@ describe("Decimal", () => {
       expect(Decimal.fromAtomics("44", 3).toString()).toEqual("0.044");
       expect(Decimal.fromAtomics("44", 4).toString()).toEqual("0.0044");
     });
+
+    it("throws for atomics that are not non-negative integers", () => {
+      expect(() => Decimal.fromAtomics("0xAA", 0)).toThrowError(
+        "Invalid string format. Only non-negative integers in decimal representation supported.",
+      );
+      expect(() => Decimal.fromAtomics("", 0)).toThrowError(
+        "Invalid string format. Only non-negative integers in decimal representation supported.",
+      );
+      expect(() => Decimal.fromAtomics("-1", 0)).toThrowError(
+        "Invalid string format. Only non-negative integers in decimal representation supported.",
+      );
+    });
   });
 
   describe("fromUserInput", () => {
diff --git a/packages/math/src/decimal.ts b/packages/math/src/decimal.ts
index 91ec2cc1..6e23489c 100644
--- a/packages/math/src/decimal.ts
+++ b/packages/math/src/decimal.ts
@@ -24,7 +24,10 @@ export class Decimal {
     let whole: string;
     let fractional: string;
 
-    if (input.search(/\./) === -1) {
+    if (input === "") {
+      whole = "0";
+      fractional = "";
+    } else if (input.search(/\./) === -1) {
       // integer format, no separator
       whole = input;
       fractional = "";
@@ -107,6 +110,12 @@ export class Decimal {
   };
 
   private constructor(atomics: string, fractionalDigits: number) {
+    if (!atomics.match(/^[0-9]+$/)) {
+      throw new Error(
+        "Invalid string format. Only non-negative integers in decimal representation supported.",
+      );
+    }
+
     this.data = {
       atomics: new BN(atomics),
       fractionalDigits: fractionalDigits,