diff --git a/Sources/CustomDump/Diff.swift b/Sources/CustomDump/Diff.swift
index ce7b340..eb14ba5 100644
--- a/Sources/CustomDump/Diff.swift
+++ b/Sources/CustomDump/Diff.swift
@@ -392,7 +392,7 @@ public func diff<T>(_ lhs: T, _ rhs: T, format: DiffFormat = .default) -> String
           }
           return lhs.key == rhs.key
         },
-        areInIncreasingOrder: T.self is _UnorderedCollection.Type
+        areInIncreasingOrder: lhsMirror.subjectType is _UnorderedCollection.Type
           ? {
             guard
               let lhs = $0.value as? (key: AnyHashable, value: Any),
@@ -483,7 +483,7 @@ public func diff<T>(_ lhs: T, _ rhs: T, format: DiffFormat = .default) -> String
         areEquivalent: {
           isIdentityEqual($0.value, $1.value) || isMirrorEqual($0.value, $1.value)
         },
-        areInIncreasingOrder: T.self is _UnorderedCollection.Type
+        areInIncreasingOrder: lhsMirror.subjectType is _UnorderedCollection.Type
           ? {
             _customDump($0.value, name: nil, indent: 0, isRoot: false, maxDepth: 1)
               < _customDump($1.value, name: nil, indent: 0, isRoot: false, maxDepth: 1)
diff --git a/Sources/CustomDump/Dump.swift b/Sources/CustomDump/Dump.swift
index fe1cfbe..35f69ea 100644
--- a/Sources/CustomDump/Dump.swift
+++ b/Sources/CustomDump/Dump.swift
@@ -209,7 +209,7 @@ func _customDump<T, TargetStream>(
         dumpChildren(
           of: mirror,
           prefix: "[", suffix: "]",
-          by: T.self is _UnorderedCollection.Type
+          by: mirror.subjectType is _UnorderedCollection.Type
             ? {
               guard
                 let (lhsKey, _) = $0.value as? (key: AnyHashable, value: Any),
@@ -262,7 +262,7 @@ func _customDump<T, TargetStream>(
       dumpChildren(
         of: mirror,
         prefix: "Set([", suffix: "])",
-        by: T.self is _UnorderedCollection.Type
+        by: mirror.subjectType is _UnorderedCollection.Type
           ? {
             _customDump($0.value, name: nil, indent: 0, isRoot: false, maxDepth: 1)
               < _customDump($1.value, name: nil, indent: 0, isRoot: false, maxDepth: 1)
diff --git a/Tests/CustomDumpTests/DumpTests.swift b/Tests/CustomDumpTests/DumpTests.swift
index a9a3cda..aeb68b8 100644
--- a/Tests/CustomDumpTests/DumpTests.swift
+++ b/Tests/CustomDumpTests/DumpTests.swift
@@ -298,7 +298,31 @@ final class DumpTests: XCTestCase {
       ]
       """
     )
+  }
+
+  func testDictionary_Nested() {
+    struct NestedDictionary {
+      let content: [String: Int]
+    }
 
+    XCTAssertNoDifference(
+      """
+      DumpTests.NestedDictionary(
+        content: [
+          "a": 5,
+          "b": 9,
+          "c": 1,
+          "d": -3,
+          "e": 12
+        ]
+      )
+      """,
+      String(
+        customDumping: NestedDictionary(
+          content: ["a": 5, "b": 9, "c": 1, "d": -3, "e": 12]
+        )
+      )
+    )
   }
 
   func testEnum() {