diff --git a/Sources/Foundation/JSONDecoder.swift b/Sources/Foundation/JSONDecoder.swift
index 503f27a337..6913494cb8 100644
--- a/Sources/Foundation/JSONDecoder.swift
+++ b/Sources/Foundation/JSONDecoder.swift
@@ -404,7 +404,7 @@ extension JSONDecoderImpl: Decoder {
         as type: T.Type) throws -> T
     {
         if case .number(let number) = value {
-            guard let floatingPoint = T(number) else {
+            guard let floatingPoint = T(number), floatingPoint.isFinite else {
                 var path = self.codingPath
                 if let additionalKey = additionalKey {
                     path.append(additionalKey)
diff --git a/Tests/Foundation/Tests/TestJSONEncoder.swift b/Tests/Foundation/Tests/TestJSONEncoder.swift
index 03a389f33d..c7e61a9b6b 100644
--- a/Tests/Foundation/Tests/TestJSONEncoder.swift
+++ b/Tests/Foundation/Tests/TestJSONEncoder.swift
@@ -601,14 +601,23 @@ class TestJSONEncoder : XCTestCase {
 
     func test_codingOfFloat() {
         test_codingOf(value: Float(1.5), toAndFrom: "1.5")
+
+        // Check value too large fails to decode.
+        XCTAssertThrowsError(try JSONDecoder().decode(Float.self, from: "1e100".data(using: .utf8)!))
     }
 
     func test_codingOfDouble() {
         test_codingOf(value: Double(1.5), toAndFrom: "1.5")
+
+        // Check value too large fails to decode.
+        XCTAssertThrowsError(try JSONDecoder().decode(Double.self, from: "100e323".data(using: .utf8)!))
     }
 
     func test_codingOfDecimal() {
         test_codingOf(value: Decimal.pi, toAndFrom: "3.14159265358979323846264338327950288419")
+
+        // Check value too large fails to decode.
+        XCTAssertThrowsError(try JSONDecoder().decode(Decimal.self, from: "100e200".data(using: .utf8)!))
     }
 
     func test_codingOfString() {