diff --git a/lib/bn.js b/lib/bn.js
index 5eba6eb..0854c1c 100644
--- a/lib/bn.js
+++ b/lib/bn.js
@@ -1915,6 +1915,9 @@
   };
 
   BN.prototype.imuln = function imuln (num) {
+    var isNegNum = num < 0;
+    if (isNegNum) num = -num;
+
     assert(typeof num === 'number');
     assert(num < 0x4000000);
 
@@ -1935,7 +1938,7 @@
       this.length++;
     }
 
-    return this;
+    return isNegNum ? this.ineg() : this;
   };
 
   BN.prototype.muln = function muln (num) {
@@ -2481,6 +2484,9 @@
   };
 
   BN.prototype.modrn = function modrn (num) {
+    var isNegNum = num < 0;
+    if (isNegNum) num = -num;
+
     assert(num <= 0x3ffffff);
     var p = (1 << 26) % num;
 
@@ -2489,7 +2495,7 @@
       acc = (p * acc + (this.words[i] | 0)) % num;
     }
 
-    return acc;
+    return isNegNum ? -acc : acc;
   };
 
   // WARNING: DEPRECATED
@@ -2499,6 +2505,9 @@
 
   // In-place division by number
   BN.prototype.idivn = function idivn (num) {
+    var isNegNum = num < 0;
+    if (isNegNum) num = -num;
+
     assert(num <= 0x3ffffff);
 
     var carry = 0;
@@ -2508,7 +2517,8 @@
       carry = w % num;
     }
 
-    return this._strip();
+    this._strip();
+    return isNegNum ? this.ineg() : this;
   };
 
   BN.prototype.divn = function divn (num) {
diff --git a/test/arithmetic-test.js b/test/arithmetic-test.js
index e9c47d4..67956ff 100644
--- a/test/arithmetic-test.js
+++ b/test/arithmetic-test.js
@@ -290,6 +290,16 @@ describe('BN.js/Arithmetic', function () {
         new BN(0).imuln(0x4000000);
       }, /^Error: Assertion failed$/);
     });
+
+    it('should negate number if number is negative', function () {
+      var a = new BN('dead', 16);
+      assert.equal(a.clone().imuln(-1).toString(16), a.clone().neg().toString(16));
+      assert.equal(a.clone().muln(-1).toString(16), a.clone().neg().toString(16));
+
+      var b = new BN('dead', 16);
+      assert.equal(b.clone().imuln(-42).toString(16), b.clone().neg().muln(42).toString(16));
+      assert.equal(b.clone().muln(-42).toString(16), b.clone().neg().muln(42).toString(16));
+    });
   });
 
   describe('.pow()', function () {
@@ -392,6 +402,7 @@ describe('BN.js/Arithmetic', function () {
   describe('.idivn()', function () {
     it('should divide numbers in-place', function () {
       assert.equal(new BN('10', 16).idivn(3).toString(16), '5');
+      assert.equal(new BN('10', 16).idivn(-3).toString(16), '-5');
       assert.equal(new BN('12', 16).idivn(3).toString(16), '6');
       assert.equal(new BN('10000000000000000').idivn(3).toString(10),
         '3333333333333333');
@@ -530,6 +541,7 @@ describe('BN.js/Arithmetic', function () {
   describe('.modrn()', function () {
     it('should act like .mod() on small numbers', function () {
       assert.equal(new BN('10', 16).modrn(256).toString(16), '10');
+      assert.equal(new BN('10', 16).modrn(-256).toString(16), '-10');
       assert.equal(new BN('100', 16).modrn(256).toString(16), '0');
       assert.equal(new BN('1001', 16).modrn(256).toString(16), '1');
       assert.equal(new BN('100000000001', 16).modrn(256).toString(16), '1');