diff --git a/Sources/Core/Tracker/Tracker.swift b/Sources/Core/Tracker/Tracker.swift
index 087d3c330..c399d5e01 100644
--- a/Sources/Core/Tracker/Tracker.swift
+++ b/Sources/Core/Tracker/Tracker.swift
@@ -431,13 +431,9 @@ class Tracker: NSObject {
         var components = URLComponents(url: url, resolvingAgainstBaseURL: false)
         let spQueryParam = URLQueryItem(name: "_sp", value: spParameters)
         
-        if let index = components?.queryItems?.firstIndex(where: { $0.name == "_sp" }) {
-            // Replace the old query item with the new one
-            components?.queryItems?[index] = spQueryParam
-        } else {
-            let queryItems = components?.queryItems ?? []
-            components?.queryItems = queryItems + [spQueryParam]
-        }
+        // Modification requires exclusive access, we must make a copy
+        var queryItems = components?.queryItems
+        components?.queryItems = (queryItems?.filter { $0.name != "_sp" } ?? []) + [spQueryParam]
         
         return components?.url
     }
diff --git a/Tests/TestLinkDecorator.swift b/Tests/TestLinkDecorator.swift
index 3b0fb9445..9bca2a119 100644
--- a/Tests/TestLinkDecorator.swift
+++ b/Tests/TestLinkDecorator.swift
@@ -114,7 +114,7 @@ class TestLinkDecorator: XCTestCase {
         
         let result = tracker.decorateLink(link, extendedParameters: CrossDeviceParameterConfiguration(sessionId: false, sourceId: false))!
         
-        matches(for: "https://example.com?a=a&_sp=\(tracker.session!.userId!).\(epoch)&b=b", in: result.absoluteString)
+        matches(for: "https://example.com?a=a&b=b&_sp=\(tracker.session!.userId!).\(epoch)&b=b", in: result.absoluteString)
     }
     
     func testMissingFields() {