diff --git a/app/features/build-analyzer/analyzer-hooks.ts b/app/features/build-analyzer/analyzer-hooks.ts
index a012e403e..24e9c4650 100644
--- a/app/features/build-analyzer/analyzer-hooks.ts
+++ b/app/features/build-analyzer/analyzer-hooks.ts
@@ -12,18 +12,20 @@ import { applySpecialEffects, SPECIAL_EFFECTS } from "./core/specialEffects";
 import { buildStats } from "./core/stats";
 import type { SpecialEffectType } from "./analyzer-types";
 import {
+  buildIsEmpty,
   buildToAbilityPoints,
   serializeBuild,
   validatedBuildFromSearchParams,
   validatedWeaponIdFromSearchParams,
 } from "./core/utils";
+import invariant from "tiny-invariant";
 
 export function useAnalyzeBuild() {
   const [searchParams, setSearchParams] = useSearchParams();
 
   const mainWeaponId = validatedWeaponIdFromSearchParams(searchParams);
   const build = validatedBuildFromSearchParams(searchParams);
-  const build2 = validatedBuildFromSearchParams(searchParams, "build2");
+  const build2 = validatedBuildFromSearchParams(searchParams, "build2", build);
   const ldeIntensity = validatedLdeIntensityFromSearchParams(searchParams);
   const effects = validatedEffectsFromSearchParams({ searchParams, build });
   const effects2 = validatedEffectsFromSearchParams({
@@ -32,6 +34,11 @@ export function useAnalyzeBuild() {
   });
   const focused = validatedFocusedFromSearchParams({ searchParams });
 
+  invariant(
+    !(buildIsEmpty(build) && !buildIsEmpty(build2)),
+    "build1 is empty but build2 isn't"
+  );
+
   const handleChange = ({
     newMainWeaponId = mainWeaponId,
     newBuild = build,
diff --git a/app/features/build-analyzer/core/utils.ts b/app/features/build-analyzer/core/utils.ts
index d9bb76850..09498ba4c 100644
--- a/app/features/build-analyzer/core/utils.ts
+++ b/app/features/build-analyzer/core/utils.ts
@@ -191,13 +191,15 @@ function validateAbility(
 
 export function validatedBuildFromSearchParams(
   searchParams: URLSearchParams,
-  key = "build"
+  key = "build",
+  otherBuild?: BuildAbilitiesTupleWithUnknown
 ): BuildAbilitiesTupleWithUnknown {
   const abilitiesArr = searchParams.get(key)
     ? searchParams.get(key)?.split(",")
     : null;
 
   if (!abilitiesArr) return EMPTY_BUILD;
+  if (otherBuild && buildIsEmpty(otherBuild)) return EMPTY_BUILD;
 
   try {
     return [