diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index e261dea..60afc98 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -14,7 +14,6 @@ jobs:
     name: Unit tests
     uses: apple/swift-nio/.github/workflows/unit_tests.yml@main
     with:
-      linux_5_10_arguments_override: "--explicit-target-dependency-import-check error"
       linux_6_0_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
       linux_6_1_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
       linux_6_2_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index 66d0822..f7fe453 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -18,7 +18,6 @@ jobs:
     name: Unit tests
     uses: apple/swift-nio/.github/workflows/unit_tests.yml@main
     with:
-      linux_5_10_arguments_override: "--explicit-target-dependency-import-check error"
       linux_6_0_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
       linux_6_1_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
       linux_6_2_arguments_override: "-Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
diff --git a/Benchmarks/Benchmarks/CertificatesBenchmark/VerifierBenchmark.swift b/Benchmarks/Benchmarks/CertificatesBenchmark/VerifierBenchmark.swift
index 0fa7b9e..824f80d 100644
--- a/Benchmarks/Benchmarks/CertificatesBenchmark/VerifierBenchmark.swift
+++ b/Benchmarks/Benchmarks/CertificatesBenchmark/VerifierBenchmark.swift
@@ -13,7 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 import Benchmark
-import X509
+@_spi(FixedExpiryValidationTime) import X509
 import Foundation
 import Crypto
 import SwiftASN1
@@ -50,7 +50,7 @@ func testTrivialChainBuilding() async -> Int {
     let roots = CertificateStore([TestCertificate.ca1])
 
     var verifier = Verifier(rootCertificates: roots) {
-        RFC5280Policy(validationTime: TestCertificate.referenceTime)
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
     }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
@@ -67,7 +67,9 @@ func testTrivialChainBuilding() async -> Int {
 func testExtraRootsAreIgnored() async -> Int {
     let roots = CertificateStore([TestCertificate.ca1, TestCertificate.ca2])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
         intermediates: CertificateStore([TestCertificate.intermediate1])
@@ -83,7 +85,9 @@ func testExtraRootsAreIgnored() async -> Int {
 func testPuttingRootsInTheIntermediariesIsntAProblem() async -> Int {
     let roots = CertificateStore([TestCertificate.ca1, TestCertificate.ca2])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
         intermediates: CertificateStore([TestCertificate.intermediate1, TestCertificate.ca1, TestCertificate.ca2])
@@ -99,7 +103,9 @@ func testPuttingRootsInTheIntermediariesIsntAProblem() async -> Int {
 func testSupportsCrossSignedRootWithoutTrouble() async -> Int {
     let roots = CertificateStore([TestCertificate.ca2])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
         intermediates: CertificateStore([TestCertificate.intermediate1, TestCertificate.ca1CrossSignedByCA2])
@@ -115,7 +121,9 @@ func testSupportsCrossSignedRootWithoutTrouble() async -> Int {
 func testBuildsTheShorterPathInTheCaseOfCrossSignedRoots() async -> Int {
     let roots = CertificateStore([TestCertificate.ca1, TestCertificate.ca2])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
         intermediates: CertificateStore([
@@ -133,7 +141,9 @@ func testBuildsTheShorterPathInTheCaseOfCrossSignedRoots() async -> Int {
 func testPrefersToUseIntermediatesWithSKIThatMatches() async -> Int {
     let roots = CertificateStore([TestCertificate.ca1])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
         intermediates: CertificateStore([TestCertificate.intermediate1, TestCertificate.intermediate1WithoutSKIAKI])
@@ -149,7 +159,9 @@ func testPrefersToUseIntermediatesWithSKIThatMatches() async -> Int {
 func testPrefersNoSKIToNonMatchingSKI() async -> Int {
     let roots = CertificateStore([TestCertificate.ca1])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
         intermediates: CertificateStore([
@@ -167,7 +179,9 @@ func testPrefersNoSKIToNonMatchingSKI() async -> Int {
 func testRejectsRootsThatDidNotSignTheCertBeforeThem() async -> Int {
     let roots = CertificateStore([TestCertificate.ca1WithAlternativePrivateKey, TestCertificate.ca2])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
         intermediates: CertificateStore([
@@ -186,7 +200,7 @@ func testPolicyFailuresCanFindLongerPaths() async -> Int {
 
     var verifier = Verifier(rootCertificates: roots) {
         FailIfCertInChainPolicy(forbiddenCert: TestCertificate.ca1)
-        RFC5280Policy(validationTime: TestCertificate.referenceTime)
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
     }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
@@ -205,7 +219,9 @@ func testPolicyFailuresCanFindLongerPaths() async -> Int {
 func testSelfSignedCertsAreTrustedWhenInTrustStore() async -> Int {
     let roots = CertificateStore([TestCertificate.ca1, TestCertificate.isolatedSelfSignedCert])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.isolatedSelfSignedCert,
         intermediates: CertificateStore([TestCertificate.intermediate1])
@@ -246,7 +262,9 @@ func testTrustRootsCanBeNonSelfSignedLeaves() async -> Int {
 func testTrustRootsCanBeNonSelfSignedIntermediates() async -> Int {
     let roots = CertificateStore([TestCertificate.intermediate1])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
         intermediates: CertificateStore([TestCertificate.intermediate1])
@@ -275,7 +293,9 @@ func testWePoliceCriticalExtensionsOnLeafCerts() async -> Int {
         TestCertificate.ca1, TestCertificate.isolatedSelfSignedCertWithWeirdCriticalExtension,
     ])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.isolatedSelfSignedCertWithWeirdCriticalExtension,
         intermediates: CertificateStore([TestCertificate.intermediate1])
@@ -291,7 +311,9 @@ func testWePoliceCriticalExtensionsOnLeafCerts() async -> Int {
 func testMissingIntermediateFailsToBuild() async -> Int {
     let roots = CertificateStore([TestCertificate.ca1])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
         intermediates: CertificateStore([])
@@ -307,7 +329,9 @@ func testMissingIntermediateFailsToBuild() async -> Int {
 func testSelfSignedCertsAreRejectedWhenNotInTheTrustStore() async -> Int {
     let roots = CertificateStore([TestCertificate.ca1])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.isolatedSelfSignedCert,
         intermediates: CertificateStore([TestCertificate.intermediate1])
@@ -322,7 +346,9 @@ func testSelfSignedCertsAreRejectedWhenNotInTheTrustStore() async -> Int {
 func testMissingRootFailsToBuild() async -> Int {
     let roots = CertificateStore([])
 
-    var verifier = Verifier(rootCertificates: roots) { RFC5280Policy(validationTime: TestCertificate.referenceTime) }
+    var verifier = Verifier(rootCertificates: roots) {
+        RFC5280Policy(fixedExpiryValidationTime: TestCertificate.referenceTime)
+    }
     let result = await verifier.validate(
         leaf: TestCertificate.localhostLeaf,
         intermediates: CertificateStore([TestCertificate.intermediate1])
diff --git a/Benchmarks/Package.swift b/Benchmarks/Package.swift
index c7856b4..4803421 100644
--- a/Benchmarks/Package.swift
+++ b/Benchmarks/Package.swift
@@ -1,4 +1,4 @@
-// swift-tools-version:5.10
+// swift-tools-version:6.0
 //===----------------------------------------------------------------------===//
 //
 // This source file is part of the SwiftCertificates open source project
diff --git a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Parse_WebPKI_Roots_from_DER.p90.json b/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Parse_WebPKI_Roots_from_DER.p90.json
deleted file mode 100644
index bed4124..0000000
--- a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Parse_WebPKI_Roots_from_DER.p90.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "mallocCountTotal" : 5728000
-}
\ No newline at end of file
diff --git a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Parse_WebPKI_Roots_from_PEM_files.p90.json b/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Parse_WebPKI_Roots_from_PEM_files.p90.json
deleted file mode 100644
index 4e53927..0000000
--- a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Parse_WebPKI_Roots_from_PEM_files.p90.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "mallocCountTotal" : 6687000
-}
\ No newline at end of file
diff --git a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Parse_WebPKI_Roots_from_multi_PEM_file.p90.json b/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Parse_WebPKI_Roots_from_multi_PEM_file.p90.json
deleted file mode 100644
index 90ff73d..0000000
--- a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Parse_WebPKI_Roots_from_multi_PEM_file.p90.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "mallocCountTotal" : 6695000
-}
\ No newline at end of file
diff --git a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.TinyArray.append.p90.json b/Benchmarks/Thresholds/5.10/CertificatesBenchmark.TinyArray.append.p90.json
deleted file mode 100644
index a739874..0000000
--- a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.TinyArray.append.p90.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "mallocCountTotal" : 10000
-}
\ No newline at end of file
diff --git a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.TinyArray_non-allocating_functions.p90.json b/Benchmarks/Thresholds/5.10/CertificatesBenchmark.TinyArray_non-allocating_functions.p90.json
deleted file mode 100644
index 9f9de44..0000000
--- a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.TinyArray_non-allocating_functions.p90.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "mallocCountTotal" : 0
-}
\ No newline at end of file
diff --git a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Verifier.p90.json b/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Verifier.p90.json
deleted file mode 100644
index 36d6c87..0000000
--- a/Benchmarks/Thresholds/5.10/CertificatesBenchmark.Verifier.p90.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "mallocCountTotal" : 918010
-}
diff --git a/Package.swift b/Package.swift
index a9a0186..e80a2be 100644
--- a/Package.swift
+++ b/Package.swift
@@ -1,4 +1,4 @@
-// swift-tools-version:5.10
+// swift-tools-version:6.0
 //===----------------------------------------------------------------------===//
 //
 // This source file is part of the SwiftCertificates open source project
@@ -85,12 +85,6 @@ if ProcessInfo.processInfo.environment["SWIFTCI_USE_LOCAL_DEPS"] == nil {
     ]
 }
 
-for target in package.targets {
-    var settings = target.swiftSettings ?? []
-    settings.append(.enableExperimentalFeature("StrictConcurrency=complete"))
-    target.swiftSettings = settings
-}
-
 // ---    STANDARD CROSS-REPO SETTINGS DO NOT EDIT   --- //
 for target in package.targets {
     switch target.type {
diff --git a/Tests/X509Tests/PEMTests.swift b/Tests/X509Tests/PEMTests.swift
index 2e37c9d..1bb2f88 100644
--- a/Tests/X509Tests/PEMTests.swift
+++ b/Tests/X509Tests/PEMTests.swift
@@ -122,7 +122,8 @@ final class PEMTests: XCTestCase {
     func testRSAPrivateKey() throws {
         // generated with "openssl genpkey -algorithm rsa"
         let rsaKey = try String(
-            contentsOf: XCTUnwrap(Bundle.module.url(forResource: "PEMTestRSACertificate", withExtension: "pem"))
+            contentsOf: XCTUnwrap(Bundle.module.url(forResource: "PEMTestRSACertificate", withExtension: "pem")),
+            encoding: .ascii
         )
         let privateKey = try Certificate.PrivateKey(pemEncoded: rsaKey)
         guard case .rsa = privateKey.backing else {