diff --git a/app/imports/parser/grammar.js b/app/imports/parser/grammar.js
index 69266b63..8e29fb16 100644
--- a/app/imports/parser/grammar.js
+++ b/app/imports/parser/grammar.js
@@ -41,6 +41,7 @@ function id(x) { return x[0]; }
     multiplicativeOperator: ['*', '/'],
     exponentOperator: ['^'],
     additiveOperator: ['+', '-'],
+    moduloOperator: ['%'],
     andOperator: ['&', '&&'],
     orOperator: ['|', '||'],
     stringDelimiters: ['\"', '\''],
@@ -75,8 +76,10 @@ let ParserRules = [
     {"name": "equalityExpression", "symbols": ["relationalExpression"], "postprocess": id},
     {"name": "relationalExpression", "symbols": ["relationalExpression", "_", (lexer.has("relationalOperator") ? {type: "relationalOperator"} : relationalOperator), "_", "additiveExpression"], "postprocess": d => operator(d, 'relation')},
     {"name": "relationalExpression", "symbols": ["additiveExpression"], "postprocess": id},
-    {"name": "additiveExpression", "symbols": ["additiveExpression", "_", (lexer.has("additiveOperator") ? {type: "additiveOperator"} : additiveOperator), "_", "multiplicativeExpression"], "postprocess": d => operator(d, 'add')},
-    {"name": "additiveExpression", "symbols": ["multiplicativeExpression"], "postprocess": id},
+    {"name": "additiveExpression", "symbols": ["additiveExpression", "_", (lexer.has("additiveOperator") ? {type: "additiveOperator"} : additiveOperator), "_", "remainderExpression"], "postprocess": d => operator(d, 'add')},
+    {"name": "additiveExpression", "symbols": ["remainderExpression"], "postprocess": id},
+    {"name": "remainderExpression", "symbols": ["remainderExpression", "_", (lexer.has("moduloOperator") ? {type: "moduloOperator"} : moduloOperator), "_", "multiplicativeExpression"], "postprocess": d => operator(d, 'remainder')},
+    {"name": "remainderExpression", "symbols": ["multiplicativeExpression"], "postprocess": id},
     {"name": "multiplicativeExpression", "symbols": ["multiplicativeExpression", "_", (lexer.has("multiplicativeOperator") ? {type: "multiplicativeOperator"} : multiplicativeOperator), "_", "rollExpression"], "postprocess": d => operator(d, 'multiply')},
     {"name": "multiplicativeExpression", "symbols": ["rollExpression"], "postprocess": id},
     {"name": "rollExpression", "symbols": ["rollExpression", "_", (lexer.has("diceOperator") ? {type: "diceOperator"} : diceOperator), "_", "exponentExpression"], "postprocess": d => new RollNode({left: d[0], right: d[4]})},
diff --git a/app/imports/parser/grammar.ne b/app/imports/parser/grammar.ne
index 066299ae..cd278bab 100644
--- a/app/imports/parser/grammar.ne
+++ b/app/imports/parser/grammar.ne
@@ -39,6 +39,7 @@
     multiplicativeOperator: ['*', '/'],
     exponentOperator: ['^'],
     additiveOperator: ['+', '-'],
+    moduloOperator: ['%'],
     andOperator: ['&', '&&'],
     orOperator: ['|', '||'],
     stringDelimiters: ['\"', '\''],
@@ -91,7 +92,11 @@ relationalExpression ->
 | additiveExpression {% id %}
 
 additiveExpression ->
-  additiveExpression _ %additiveOperator _ multiplicativeExpression {% d => operator(d, 'add') %}
+  additiveExpression _ %additiveOperator _ remainderExpression {% d => operator(d, 'add') %}
+| remainderExpression {% id %}
+
+remainderExpression ->
+  remainderExpression _ %moduloOperator _ multiplicativeExpression {% d => operator(d, 'remainder') %}
 | multiplicativeExpression {% id %}
 
 multiplicativeExpression ->
diff --git a/app/imports/parser/parseTree/OperatorNode.js b/app/imports/parser/parseTree/OperatorNode.js
index e6822abf..6fe63428 100644
--- a/app/imports/parser/parseTree/OperatorNode.js
+++ b/app/imports/parser/parseTree/OperatorNode.js
@@ -31,6 +31,7 @@ export default class OperatorNode extends ParseNode {
       case '*': result = left * right; break;
       case '/': result = left / right; break;
       case '^': result = Math.pow(left, right); break;
+      case '%': result = left % right; break;
       case '&':
       case '&&': result = left && right; break;
       case '|':