diff --git a/Sources/SwiftExtract/SwiftTypes/SwiftType.swift b/Sources/SwiftExtract/SwiftTypes/SwiftType.swift
index 0cb2fedf0..89dc2baf0 100644
--- a/Sources/SwiftExtract/SwiftTypes/SwiftType.swift
+++ b/Sources/SwiftExtract/SwiftTypes/SwiftType.swift
@@ -521,7 +521,7 @@ extension SwiftType {
       if someOrAntType.someOrAnySpecifier.tokenKind == .keyword(.some) {
         self = .opaque(try SwiftType(someOrAntType.constraint, lookupContext: lookupContext))
       } else {
-        self = .opaque(try SwiftType(someOrAntType.constraint, lookupContext: lookupContext))
+        self = .existential(try SwiftType(someOrAntType.constraint, lookupContext: lookupContext))
       }
 
     case .compositionType(let compositeType):
diff --git a/Tests/SwiftExtractTests/AnalysisResultTests.swift b/Tests/SwiftExtractTests/AnalysisResultTests.swift
index 2fc1abd25..e734fe176 100644
--- a/Tests/SwiftExtractTests/AnalysisResultTests.swift
+++ b/Tests/SwiftExtractTests/AnalysisResultTests.swift
@@ -393,6 +393,39 @@ struct AnalysisResultSuite {
     #expect(unresolvable.functionSignature.thrownTypedError == nil)
   }
 
+  @Test
+  func someAndAnyProduceOpaqueAndExistentialTypes() throws {
+    let result = try analyze(
+      sources: [
+        (
+          "/fake/Source.swift",
+          """
+          public protocol Swimmer {}
+          public func trainOpaque(_ swimmer: some Swimmer) {}
+          public func trainExistential(_ swimmer: any Swimmer) {}
+          """
+        )
+      ],
+      moduleName: "Aquarium"
+    )
+
+    let byName = Dictionary(uniqueKeysWithValues: result.extractedGlobalFuncs.map { ($0.name, $0) })
+
+    let opaque = try #require(byName["trainOpaque"]?.functionSignature.parameters.first?.type)
+    guard case .opaque = opaque else {
+      Issue.record("expected .opaque, got \(opaque)")
+      return
+    }
+    #expect(opaque.description == "some Swimmer")
+
+    let existential = try #require(byName["trainExistential"]?.functionSignature.parameters.first?.type)
+    guard case .existential = existential else {
+      Issue.record("expected .existential, got \(existential)")
+      return
+    }
+    #expect(existential.description == "any Swimmer")
+  }
+
   @Test
   func typedThrowsOnInitializers() throws {
     let result = try analyze(