diff --git a/CHANGELOG.md b/CHANGELOG.md
index 40a7617..f56bcdd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   authenticated UI via `<img src="…">`.
 
 ### Fixed
+- `PriceRequest::toQuery()` now gives every package its own indexed query
+  parameters (`weightInGrams0`, `length0`, …, `weightInGrams1`, …) when a
+  request carries more than one package. The previous shape repeated the bare
+  key (`weightInGrams=1200&weightInGrams=800`), which Shipping Guide v2
+  collapses to a single value — so a 2-, 3- or 20-package request was priced
+  as one package and every quote came back identical regardless of package
+  count. A single-package request keeps the unsuffixed names it always used.
 - `PriceRequest::toQuery()` now serialises the `product` query parameter
   as Bring's numeric service code (via the new `Product::shippingGuideCode()`)
   instead of the v2 string name. Shipping Guide v2 prices by numeric code,
diff --git a/src/v4/Endpoint/Shipping/PriceRequest.php b/src/v4/Endpoint/Shipping/PriceRequest.php
index d2c82bf..61e6a08 100644
--- a/src/v4/Endpoint/Shipping/PriceRequest.php
+++ b/src/v4/Endpoint/Shipping/PriceRequest.php
@@ -67,16 +67,25 @@ public function toQuery(): array
             'toPostalCode' => $this->toPostalCode,
         ];
 
-        foreach ($this->packages as $i => $pkg) {
-            $q['weightInGrams'][$i] = (int) $pkg['weightInGrams'];
+        // Shipping Guide v2 addresses each package by an index *suffix* on the
+        // parameter name (weightInGrams0, length0, ..., weightInGrams1, ...) —
+        // not by a repeated bare key. A repeated `weightInGrams` is collapsed to
+        // a single value server-side, so every multi-package request was priced
+        // as one package. A lone package keeps the unsuffixed names, which is
+        // what the API documents for the single-package case.
+        $packages = array_values($this->packages);
+        $multiple = \count($packages) > 1;
+        foreach ($packages as $i => $pkg) {
+            $suffix = $multiple ? (string) $i : '';
+            $q['weightInGrams'.$suffix] = (int) $pkg['weightInGrams'];
             if (isset($pkg['length'])) {
-                $q['length'][$i] = (int) $pkg['length'];
+                $q['length'.$suffix] = (int) $pkg['length'];
             }
             if (isset($pkg['width'])) {
-                $q['width'][$i] = (int) $pkg['width'];
+                $q['width'.$suffix] = (int) $pkg['width'];
             }
             if (isset($pkg['height'])) {
-                $q['height'][$i] = (int) $pkg['height'];
+                $q['height'.$suffix] = (int) $pkg['height'];
             }
         }
 
diff --git a/tests/v4/Endpoint/Shipping/PriceRequestTest.php b/tests/v4/Endpoint/Shipping/PriceRequestTest.php
index 67b3894..abcdd60 100644
--- a/tests/v4/Endpoint/Shipping/PriceRequestTest.php
+++ b/tests/v4/Endpoint/Shipping/PriceRequestTest.php
@@ -55,4 +55,47 @@ public function testNoProductParamWhenProductsEmpty(): void
     {
         self::assertArrayNotHasKey('product', $this->request()->toQuery());
     }
+
+    public function testSinglePackageUsesUnsuffixedParameterNames(): void
+    {
+        $q = (new PriceRequest(
+            fromCountry: Country::NO,
+            fromPostalCode: '1712',
+            toCountry: Country::NO,
+            toPostalCode: '0150',
+            packages: [['weightInGrams' => 1000, 'length' => 30, 'width' => 20, 'height' => 15]],
+        ))->toQuery();
+
+        self::assertSame(1000, $q['weightInGrams']);
+        self::assertSame(30, $q['length']);
+        self::assertSame(20, $q['width']);
+        self::assertSame(15, $q['height']);
+    }
+
+    public function testEachPackageGetsItsOwnIndexedParameters(): void
+    {
+        // Bring indexes multi-package requests by suffixing the parameter name.
+        // Repeating a bare `weightInGrams` loses every package but one, which is
+        // what made the price identical for 1, 2 and 20 packages.
+        $q = (new PriceRequest(
+            fromCountry: Country::NO,
+            fromPostalCode: '1712',
+            toCountry: Country::NO,
+            toPostalCode: '0150',
+            packages: [
+                ['weightInGrams' => 1000, 'length' => 30, 'width' => 20, 'height' => 15],
+                ['weightInGrams' => 2500],
+                ['weightInGrams' => 400],
+            ],
+        ))->toQuery();
+
+        self::assertSame(1000, $q['weightInGrams0']);
+        self::assertSame(2500, $q['weightInGrams1']);
+        self::assertSame(400, $q['weightInGrams2']);
+        self::assertSame(30, $q['length0']);
+        self::assertSame(20, $q['width0']);
+        self::assertSame(15, $q['height0']);
+        self::assertArrayNotHasKey('weightInGrams', $q);
+        self::assertArrayNotHasKey('length1', $q);
+    }
 }
diff --git a/tests/v4/Http/TransportTest.php b/tests/v4/Http/TransportTest.php
index e52af47..0d63a5a 100644
--- a/tests/v4/Http/TransportTest.php
+++ b/tests/v4/Http/TransportTest.php
@@ -178,7 +178,7 @@ public function testGuzzleBadResponseExceptionSurfacesAsBringApiException(): voi
         }
     }
 
-    public function testShippingPriceQueryBuildsBareRepeatedKeys(): void
+    public function testShippingPriceQueryIndexesEachPackage(): void
     {
         $client = new RecordingClient([new Response(200, ['Content-Type' => 'application/json'], '{"Product":[]}')]);
         $transport = new Transport($client, $this->factory, $this->factory, $this->factory, new NullAuthorization());
@@ -193,11 +193,32 @@ public function testShippingPriceQueryBuildsBareRepeatedKeys(): void
         $transport->send(new PriceEndpoint($request));
 
         $uri = (string) $client->lastRequest()->getUri();
-        // Repeated weightInGrams without [0]/[1] subscripts (Bring's expected format).
-        self::assertStringContainsString('weightInGrams=1200', $uri);
-        self::assertStringContainsString('weightInGrams=800', $uri);
+        // Shipping Guide v2 needs one suffixed parameter per package; a repeated
+        // bare `weightInGrams` is collapsed server-side and prices one package.
+        self::assertStringContainsString('weightInGrams0=1200', $uri);
+        self::assertStringContainsString('weightInGrams1=800', $uri);
+        self::assertStringNotContainsString('weightInGrams=', $uri);
         self::assertStringNotContainsString('weightInGrams%5B0%5D=', $uri);
-        self::assertStringNotContainsString('weightInGrams[0]=', $uri);
+    }
+
+    public function testShippingPriceQueryKeepsBareKeysForASinglePackage(): void
+    {
+        $client = new RecordingClient([new Response(200, ['Content-Type' => 'application/json'], '{"Product":[]}')]);
+        $transport = new Transport($client, $this->factory, $this->factory, $this->factory, new NullAuthorization());
+
+        $request = new PriceRequest(
+            fromCountry: Country::NO,
+            fromPostalCode: '0150',
+            toCountry: Country::NO,
+            toPostalCode: '5003',
+            packages: [['weightInGrams' => 1200, 'length' => 30, 'width' => 20, 'height' => 15]],
+        );
+        $transport->send(new PriceEndpoint($request));
+
+        $uri = (string) $client->lastRequest()->getUri();
+        self::assertStringContainsString('weightInGrams=1200', $uri);
+        self::assertStringContainsString('length=30', $uri);
+        self::assertStringNotContainsString('weightInGrams0=', $uri);
     }
 
     public function testPostalCodeRequestUrl(): void