diff --git a/src/browser/ColorManager.ts b/src/browser/ColorManager.ts
index bc0d0a4e..c1797d76 100644
--- a/src/browser/ColorManager.ts
+++ b/src/browser/ColorManager.ts
@@ -163,8 +163,9 @@ export class ColorManager implements IColorManager {
     this.colors.ansi[14] = this._parseColor(theme.brightCyan, DEFAULT_ANSI_COLORS[14]);
     this.colors.ansi[15] = this._parseColor(theme.brightWhite, DEFAULT_ANSI_COLORS[15]);
     if (theme.extendedAnsi) {
-      for (let ansiColor = 0; ansiColor < theme.extendedAnsi.length && ansiColor <= 255 - 16; ansiColor++) {
-        this.colors.ansi[ansiColor + 16] = this._parseColor(theme.extendedAnsi[ansiColor], DEFAULT_ANSI_COLORS[ansiColor + 16]);
+      const colorCount = Math.max(theme.extendedAnsi.length + 16, 256);
+      for (let i = 16; i < colorCount; i++) {
+        this.colors.ansi[i] = this._parseColor(theme.extendedAnsi[i - 16], DEFAULT_ANSI_COLORS[i]);
       }
     }
     // Clear our the cache