diff --git a/packages/mermaid/src/themes/theme-neo.js b/packages/mermaid/src/themes/theme-neo.js
index 4b0fea02c..3bc036c11 100644
--- a/packages/mermaid/src/themes/theme-neo.js
+++ b/packages/mermaid/src/themes/theme-neo.js
@@ -119,6 +119,10 @@ class Theme {
     this.taskTextDarkColor = this.taskTextDarkColor || this.textColor;
     this.taskTextClickableColor = this.taskTextClickableColor || '#003163';
 
+    /* Architecture Diagram variables */
+    this.archEdgeColor = this.lineColor;
+    this.archEdgeArrowColor = this.lineColor;
+
     /* Sequence Diagram variables */
 
     this.personBorder = this.personBorder || this.primaryBorderColor;