diff --git a/Sources/RawStructuredFieldValues/PseudoDecimal.swift b/Sources/RawStructuredFieldValues/PseudoDecimal.swift
index e5cf92c..d2c2ec4 100644
--- a/Sources/RawStructuredFieldValues/PseudoDecimal.swift
+++ b/Sources/RawStructuredFieldValues/PseudoDecimal.swift
@@ -226,6 +226,7 @@ extension String {
 // Swift Numerics would let us do this for all the floating point types.
 extension Double {
     public init(_ pseudoDecimal: PseudoDecimal) {
-        self = Double(pseudoDecimal.mantissa) * pow(10, Double(pseudoDecimal.exponent))
+        // Divide by an exact power of ten: multiplying by an inexact negative power of ten rounds twice.
+        self = Double(pseudoDecimal.mantissa) / pow(10, -Double(pseudoDecimal.exponent))
     }
 }
diff --git a/Tests/StructuredFieldValuesTests/StructuredFieldDecoderTests.swift b/Tests/StructuredFieldValuesTests/StructuredFieldDecoderTests.swift
index d56350a..5082d9c 100644
--- a/Tests/StructuredFieldValuesTests/StructuredFieldDecoderTests.swift
+++ b/Tests/StructuredFieldValuesTests/StructuredFieldDecoderTests.swift
@@ -182,6 +182,14 @@ final class StructuredFieldDecoderTests: XCTestCase {
         XCTAssertEqual(ItemField(Double(5.0)), try StructuredFieldValueDecoder().decode(from: Array(headerField.utf8)))
     }
 
+    func testDecodingDecimalAsDoubleIsCorrectlyRounded() throws {
+        XCTAssertEqual(ItemField(Double(0.3)), try StructuredFieldValueDecoder().decode(from: Array("0.3".utf8)))
+        XCTAssertEqual(
+            ItemField(Double(-19.993)),
+            try StructuredFieldValueDecoder().decode(from: Array("-19.993".utf8))
+        )
+    }
+
     func testAskingForTheWrongType() throws {
         let headerField = "gzip"
         let intField = "5"