diff --git a/src/themes/theme-base.js b/src/themes/theme-base.js
index e90a1b0f5..fdf5d8848 100644
--- a/src/themes/theme-base.js
+++ b/src/themes/theme-base.js
@@ -64,9 +64,8 @@ class Theme {
     this.defaultLinkColor = this.defaultLinkColor || this.lineColor;
     this.titleColor = this.titleColor || this.tertiaryTextColor;
     this.edgeLabelBackground =
-      this.edgeLabelBackground || this.darkMode
-        ? darken(this.secondaryColor, 30)
-        : this.secondaryColor;
+      this.edgeLabelBackground ||
+      (this.darkMode ? darken(this.secondaryColor, 30) : this.secondaryColor);
     this.nodeTextColor = this.nodeTextColor || this.primaryTextColor;
     /* Sequence Diagram variables */