diff --git a/packages/mermaid/src/diagrams/flowchart/flowDb.js b/packages/mermaid/src/diagrams/flowchart/flowDb.js
index a87bf558de..9c9442ce27 100644
--- a/packages/mermaid/src/diagrams/flowchart/flowDb.js
+++ b/packages/mermaid/src/diagrams/flowchart/flowDb.js
@@ -192,6 +192,12 @@ export const updateLinkInterpolate = function (positions, interp) {
  */
 export const updateLink = function (positions, style) {
   positions.forEach(function (pos) {
+    if (pos >= edges.length) {
+      let error = new Error(
+        `Incorrect index ${pos} of linkStyle. (Help: Index must be from 0 to ${edges.length - 1})`
+      );
+      throw error;
+    }
     if (pos === 'default') {
       edges.defaultStyle = style;
     } else {
diff --git a/packages/mermaid/src/diagrams/flowchart/parser/flow-style.spec.js b/packages/mermaid/src/diagrams/flowchart/parser/flow-style.spec.js
index 1ab7543085..eb56c24f39 100644
--- a/packages/mermaid/src/diagrams/flowchart/parser/flow-style.spec.js
+++ b/packages/mermaid/src/diagrams/flowchart/parser/flow-style.spec.js
@@ -286,6 +286,14 @@ describe('[Style] when parsing', () => {
     expect(edges[0].type).toBe('arrow_point');
   });
 
+  it('should handle style definitions within number of edges', function () {
+    const res = flow.parser.parse('graph TD\n' + 'A-->B\n' + 'linkStyle 0 stroke-width:1px;');
+
+    const edges = flow.parser.yy.getEdges();
+
+    expect(edges[0].style[0]).toBe('stroke-width:1px');
+  });
+
   it('should handle multi-numbered style definitions with more then 1 digit in a row', function () {
     const res = flow.parser.parse(
       'graph TD\n' +