diff --git a/dom/animation/KeyframeUtils.cpp b/dom/animation/KeyframeUtils.cpp
index c65f1c97f589..190beea32d3f 100644
--- a/dom/animation/KeyframeUtils.cpp
+++ b/dom/animation/KeyframeUtils.cpp
@@ -11,6 +11,7 @@
 #include "mozilla/RangedArray.h"
 #include "mozilla/ServoBindings.h"
 #include "mozilla/ServoBindingTypes.h"
+#include "mozilla/ServoCSSParser.h"
 #include "mozilla/StyleAnimationValue.h"
 #include "mozilla/TimingParams.h"
 #include "mozilla/dom/BaseKeyframeTypesBinding.h" // For FastBaseKeyframe etc.
@@ -560,26 +561,6 @@ KeyframeUtils::IsAnimatableProperty(nsCSSPropertyID aProperty,
   return false;
 }
 
-/* static */ already_AddRefed<RawServoDeclarationBlock>
-KeyframeUtils::ParseProperty(nsCSSPropertyID aProperty,
-                             const nsAString& aValue,
-                             nsIDocument* aDocument)
-{
-  MOZ_ASSERT(aDocument);
-
-  NS_ConvertUTF16toUTF8 value(aValue);
-  // FIXME this is using the wrong base uri (bug 1343919)
-  RefPtr<URLExtraData> data = new URLExtraData(aDocument->GetDocumentURI(),
-                                               aDocument->GetDocumentURI(),
-                                               aDocument->NodePrincipal());
-  return Servo_ParseProperty(aProperty,
-                             &value,
-                             data,
-                             ParsingMode::Default,
-                             aDocument->GetCompatibilityMode(),
-                             aDocument->CSSLoader()).Consume();
-}
-
 // ------------------------------------------------------------------
 //
 // Internal helpers
@@ -903,8 +884,10 @@ MakePropertyValuePair(nsCSSPropertyID aProperty, const nsAString& aStringValue,
   Maybe<PropertyValuePair> result;
 
   if (aDocument->GetStyleBackendType() == StyleBackendType::Servo) {
+    ServoCSSParser::ParsingEnvironment env =
+      ServoCSSParser::GetParsingEnvironment(aDocument);
     RefPtr<RawServoDeclarationBlock> servoDeclarationBlock =
-      KeyframeUtils::ParseProperty(aProperty, aStringValue, aDocument);
+      ServoCSSParser::ParseProperty(aProperty, aStringValue, env);
 
     if (servoDeclarationBlock) {
       result.emplace(aProperty, Move(servoDeclarationBlock));
diff --git a/dom/animation/KeyframeUtils.h b/dom/animation/KeyframeUtils.h
index 006d3b8c2ffe..1c675c6fb226 100644
--- a/dom/animation/KeyframeUtils.h
+++ b/dom/animation/KeyframeUtils.h
@@ -107,22 +107,6 @@ public:
    */
   static bool IsAnimatableProperty(nsCSSPropertyID aProperty,
                                    StyleBackendType aBackend);
-
-  /**
-   * Parse a string representing a CSS property value into a
-   * RawServoDeclarationBlock.
-   *
-   * @param aProperty The property to be parsed.
-   * @param aValue The specified value.
-   * @param aDocument The current document.
-   * @return The parsed value as a RawServoDeclarationBlock. We put the value
-   *   in a declaration block since that is how we represent specified values
-   *   in Servo.
-   */
-  static already_AddRefed<RawServoDeclarationBlock> ParseProperty(
-    nsCSSPropertyID aProperty,
-    const nsAString& aValue,
-    nsIDocument* aDocument);
 };
 
 } // namespace mozilla
diff --git a/dom/animation/TimingParams.cpp b/dom/animation/TimingParams.cpp
index 29c886955122..98e677ea37e6 100644
--- a/dom/animation/TimingParams.cpp
+++ b/dom/animation/TimingParams.cpp
@@ -10,7 +10,7 @@
 #include "mozilla/dom/AnimatableBinding.h"
 #include "mozilla/dom/KeyframeAnimationOptionsBinding.h"
 #include "mozilla/dom/KeyframeEffectBinding.h"
-#include "mozilla/ServoBindings.h"
+#include "mozilla/ServoCSSParser.h"
 #include "nsCSSParser.h" // For nsCSSParser
 #include "nsIDocument.h"
 #include "nsRuleNode.h"
@@ -119,11 +119,8 @@ TimingParams::ParseEasing(const nsAString& aEasing,
 
   if (aDocument->IsStyledByServo()) {
     nsTimingFunction timingFunction;
-    // FIXME this is using the wrong base uri (bug 1343919)
-    RefPtr<URLExtraData> data = new URLExtraData(aDocument->GetDocumentURI(),
-                                                 aDocument->GetDocumentURI(),
-                                                 aDocument->NodePrincipal());
-    if (!Servo_ParseEasing(&aEasing, data, &timingFunction)) {
+    RefPtr<URLExtraData> url = ServoCSSParser::GetURLExtraData(aDocument);
+    if (!ServoCSSParser::ParseEasing(aEasing, url, timingFunction)) {
       aRv.ThrowTypeError<dom::MSG_INVALID_EASING_ERROR>(aEasing);
       return Nothing();
     }
diff --git a/dom/base/DOMMatrix.cpp b/dom/base/DOMMatrix.cpp
index ca94e0b68b26..64ba49c452a2 100644
--- a/dom/base/DOMMatrix.cpp
+++ b/dom/base/DOMMatrix.cpp
@@ -12,7 +12,7 @@
 #include "mozilla/dom/DOMPointBinding.h"
 #include "mozilla/dom/BindingDeclarations.h"
 #include "mozilla/dom/ToJSValue.h"
-#include "mozilla/ServoBindings.h"
+#include "mozilla/ServoCSSParser.h"
 #include "nsCSSParser.h"
 #include "nsStyleTransformMatrix.h"
 
@@ -676,10 +676,9 @@ DOMMatrix::SetMatrixValue(const nsAString& aTransformList, ErrorResult& aRv)
   gfx::Matrix4x4 transform;
   bool contains3dTransform = false;
   if (mIsServo) {
-    bool status = Servo_ParseTransformIntoMatrix(&aTransformList,
-                                                 &contains3dTransform,
-                                                 &transform.components);
-    if (!status) {
+    if (!ServoCSSParser::ParseTransformIntoMatrix(aTransformList,
+                                                  contains3dTransform,
+                                                  transform.components)) {
       aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
       return nullptr;
     }
diff --git a/dom/canvas/CanvasRenderingContext2D.cpp b/dom/canvas/CanvasRenderingContext2D.cpp
index 5cfbb908aaa6..128d4c10fcdc 100644
--- a/dom/canvas/CanvasRenderingContext2D.cpp
+++ b/dom/canvas/CanvasRenderingContext2D.cpp
@@ -2841,15 +2841,11 @@ CreateDeclarationForServo(nsCSSPropertyID aProperty,
                      aDocument->GetDocumentURI(),
                      aDocument->NodePrincipal());
 
-  NS_ConvertUTF16toUTF8 value(aPropertyValue);
-
+  ServoCSSParser::ParsingEnvironment env(data,
+                                         aDocument->GetCompatibilityMode(),
+                                         aDocument->CSSLoader());
   RefPtr<RawServoDeclarationBlock> servoDeclarations =
-    Servo_ParseProperty(aProperty,
-                        &value,
-                        data,
-                        ParsingMode::Default,
-                        aDocument->GetCompatibilityMode(),
-                        aDocument->CSSLoader()).Consume();
+    ServoCSSParser::ParseProperty(aProperty, aPropertyValue, env);
 
   if (!servoDeclarations) {
     // We got a syntax error.  The spec says this value must be ignored.
diff --git a/dom/smil/nsSMILCSSValueType.cpp b/dom/smil/nsSMILCSSValueType.cpp
index 6e90546d6a36..8d694623048a 100644
--- a/dom/smil/nsSMILCSSValueType.cpp
+++ b/dom/smil/nsSMILCSSValueType.cpp
@@ -18,6 +18,7 @@
 #include "nsPresContext.h"
 #include "mozilla/ServoBindings.h"
 #include "mozilla/StyleAnimationValue.h" // For AnimationValue
+#include "mozilla/ServoCSSParser.h"
 #include "mozilla/StyleSetHandleInlines.h"
 #include "mozilla/dom/BaseKeyframeTypesBinding.h" // For CompositeOperation
 #include "mozilla/dom/Element.h"
@@ -712,19 +713,12 @@ ValueFromStringHelper(nsCSSPropertyID aPropID,
   }
 
   // Parse property
-  // FIXME this is using the wrong base uri (bug 1343919)
-  RefPtr<URLExtraData> data = new URLExtraData(doc->GetDocumentURI(),
-                                               doc->GetDocumentURI(),
-                                               doc->NodePrincipal());
-  NS_ConvertUTF16toUTF8 value(aString);
+  ServoCSSParser::ParsingEnvironment env =
+    ServoCSSParser::GetParsingEnvironment(doc);
   RefPtr<RawServoDeclarationBlock> servoDeclarationBlock =
-    Servo_ParseProperty(aPropID,
-                        &value,
-                        data,
-                        ParsingMode::AllowUnitlessLength |
-                        ParsingMode::AllowAllNumericValues,
-                        doc->GetCompatibilityMode(),
-                        doc->CSSLoader()).Consume();
+    ServoCSSParser::ParseProperty(aPropID, aString, env,
+                                  ParsingMode::AllowUnitlessLength |
+                                    ParsingMode::AllowAllNumericValues);
   if (!servoDeclarationBlock) {
     return result;
   }
diff --git a/layout/style/FontFace.cpp b/layout/style/FontFace.cpp
index 295087fc166b..1c66aee09b7e 100644
--- a/layout/style/FontFace.cpp
+++ b/layout/style/FontFace.cpp
@@ -13,6 +13,7 @@
 #include "mozilla/dom/TypedArray.h"
 #include "mozilla/dom/UnionTypes.h"
 #include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/ServoCSSParser.h"
 #include "mozilla/ServoStyleSet.h"
 #include "mozilla/ServoUtils.h"
 #include "nsCSSFontFaceRule.h"
@@ -522,7 +523,7 @@ FontFace::ParseDescriptor(nsCSSFontDesc aDescID,
 
   if (mFontFaceSet->Document()->IsStyledByServo()) {
     RefPtr<URLExtraData> url = new URLExtraData(base, docURI, principal);
-    return Servo_ParseFontDescriptor(aDescID, &aString, url, &aResult);
+    return ServoCSSParser::ParseFontDescriptor(aDescID, aString, url, aResult);
   }
 
   nsCSSParser parser;
diff --git a/layout/style/FontFaceSet.cpp b/layout/style/FontFaceSet.cpp
index 62f1a7a7e4e7..0653c0c897de 100644
--- a/layout/style/FontFaceSet.cpp
+++ b/layout/style/FontFaceSet.cpp
@@ -20,6 +20,7 @@
 #include "mozilla/AsyncEventDispatcher.h"
 #include "mozilla/Logging.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/ServoCSSParser.h"
 #include "mozilla/ServoStyleSet.h"
 #include "mozilla/ServoUtils.h"
 #include "mozilla/Sprintf.h"
@@ -210,12 +211,9 @@ FontFaceSet::ParseFontShorthandForMatching(
     nsCSSValue style;
     nsCSSValue stretch;
     nsCSSValue weight;
-    // Bug 1343919: The Base URI is not correct.
-    RefPtr<URLExtraData> url = new URLExtraData(mDocument->GetDocumentURI(),
-                                                mDocument->GetDocumentURI(),
-                                                mDocument->NodePrincipal());
-    if (!Servo_ParseFontShorthandForMatching(
-          &aFont, url, &aFamilyList, &style, &stretch, &weight)) {
+    RefPtr<URLExtraData> url = ServoCSSParser::GetURLExtraData(mDocument);
+    if (!ServoCSSParser::ParseFontShorthandForMatching(
+          aFont, url, aFamilyList, style, stretch, weight)) {
       aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
       return;
     }
diff --git a/layout/style/ServoCSSParser.cpp b/layout/style/ServoCSSParser.cpp
index 6b244483bc6a..3ea8a6e33dd7 100644
--- a/layout/style/ServoCSSParser.cpp
+++ b/layout/style/ServoCSSParser.cpp
@@ -8,6 +8,9 @@
 
 #include "ServoCSSParser.h"
 
+#include "mozilla/ServoBindings.h"
+#include "nsIDocument.h"
+
 using namespace mozilla;
 
 /* static */ bool
@@ -54,3 +57,77 @@ ServoCSSParser::ParseCounterStyleDescriptor(nsCSSCounterDesc aDescriptor,
   return Servo_ParseCounterStyleDescriptor(aDescriptor, &value, aURLExtraData,
                                            &aResult);
 }
+
+/* static */ already_AddRefed<RawServoDeclarationBlock>
+ServoCSSParser::ParseProperty(nsCSSPropertyID aProperty,
+                              const nsAString& aValue,
+                              const ParsingEnvironment& aParsingEnvironment,
+                              ParsingMode aParsingMode)
+{
+  NS_ConvertUTF16toUTF8 value(aValue);
+  return Servo_ParseProperty(aProperty,
+                             &value,
+                             aParsingEnvironment.mUrlExtraData,
+                             aParsingMode,
+                             aParsingEnvironment.mCompatMode,
+                             aParsingEnvironment.mLoader).Consume();
+}
+
+/* static */ bool
+ServoCSSParser::ParseEasing(const nsAString& aValue,
+                            URLExtraData* aUrl,
+                            nsTimingFunction& aResult)
+{
+  return Servo_ParseEasing(&aValue, aUrl, &aResult);
+}
+
+/* static */ bool
+ServoCSSParser::ParseTransformIntoMatrix(const nsAString& aValue,
+                                         bool& aContains3DTransform,
+                                         RawGeckoGfxMatrix4x4& aResult)
+{
+  return Servo_ParseTransformIntoMatrix(&aValue,
+                                        &aContains3DTransform,
+                                        &aResult);
+}
+
+/* static */ bool
+ServoCSSParser::ParseFontDescriptor(nsCSSFontDesc aDescID,
+                                    const nsAString& aValue,
+                                    URLExtraData* aUrl,
+                                    nsCSSValue& aResult)
+{
+  return Servo_ParseFontDescriptor(aDescID, &aValue, aUrl, &aResult);
+}
+
+/* static */ bool
+ServoCSSParser::ParseFontShorthandForMatching(const nsAString& aValue,
+                                              URLExtraData* aUrl,
+                                              RefPtr<SharedFontList>& aList,
+                                              nsCSSValue& aStyle,
+                                              nsCSSValue& aStretch,
+                                              nsCSSValue& aWeight)
+{
+  return Servo_ParseFontShorthandForMatching(&aValue, aUrl, &aList,
+                                             &aStyle, &aStretch, &aWeight);
+}
+
+/* static */ already_AddRefed<URLExtraData>
+ServoCSSParser::GetURLExtraData(nsIDocument* aDocument)
+{
+  MOZ_ASSERT(aDocument);
+
+  // FIXME this is using the wrong base uri (bug 1343919)
+  RefPtr<URLExtraData> url = new URLExtraData(aDocument->GetDocumentURI(),
+                                              aDocument->GetDocumentURI(),
+                                              aDocument->NodePrincipal());
+  return url.forget();
+}
+
+/* static */ ServoCSSParser::ParsingEnvironment
+ServoCSSParser::GetParsingEnvironment(nsIDocument* aDocument)
+{
+  return ParsingEnvironment(GetURLExtraData(aDocument),
+                            aDocument->GetCompatibilityMode(),
+                            aDocument->CSSLoader());
+}
diff --git a/layout/style/ServoCSSParser.h b/layout/style/ServoCSSParser.h
index 9495bcc9fa29..17206b84cce1 100644
--- a/layout/style/ServoCSSParser.h
+++ b/layout/style/ServoCSSParser.h
@@ -9,7 +9,19 @@
 #ifndef mozilla_ServoCSSParser_h
 #define mozilla_ServoCSSParser_h
 
-#include "mozilla/ServoBindings.h"
+#include "mozilla/gfx/Types.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/ServoTypes.h"
+#include "nsColor.h"
+#include "nsCSSPropertyID.h"
+#include "nsDOMCSSDeclaration.h"
+#include "nsString.h"
+
+class nsCSSValue;
+class nsIDocument;
+struct nsCSSRect;
+
+using RawGeckoGfxMatrix4x4 = mozilla::gfx::Float[16];
 
 namespace mozilla {
 namespace css {
@@ -19,9 +31,15 @@ class Loader;
 
 namespace mozilla {
 
+class ServoStyleSet;
+class SharedFontList;
+struct URLExtraData;
+
 class ServoCSSParser
 {
 public:
+  using ParsingEnvironment = nsDOMCSSDeclaration::ServoCSSParsingEnvironment;
+
   /**
    * Returns whether the specified string can be parsed as a valid CSS
    * <color> value.
@@ -87,6 +105,98 @@ public:
                               const nsAString& aValue,
                               URLExtraData* aURLExtraData,
                               nsCSSValue& aResult);
+
+  /**
+   * Parse a string representing a CSS property value into a
+   * RawServoDeclarationBlock.
+   *
+   * @param aProperty The property to be parsed.
+   * @param aValue The specified value.
+   * @param aParsingEnvironment All the parsing environment data we need.
+   * @param aParsingMode The paring mode we apply.
+   * @return The parsed value as a RawServoDeclarationBlock. We put the value
+   *   in a declaration block since that is how we represent specified values
+   *   in Servo.
+   */
+  static already_AddRefed<RawServoDeclarationBlock> ParseProperty(
+    nsCSSPropertyID aProperty,
+    const nsAString& aValue,
+    const ParsingEnvironment& aParsingEnvironment,
+    ParsingMode aParsingMode = ParsingMode::Default);
+
+  /**
+   * Parse a animation timing function.
+   *
+   * @param aValue The specified value.
+   * @param aUrl The parser url extra data.
+   * @param aResult The output timing function. (output)
+   * @return Whether the value was successfully parsed.
+   */
+  static bool ParseEasing(const nsAString& aValue,
+                          URLExtraData* aUrl,
+                          nsTimingFunction& aResult);
+
+  /**
+   * Parse a specified transform list into a gfx matrix.
+   *
+   * @param aValue The specified value.
+   * @param aContains3DTransform The output flag indicates whether this is any
+   *   3d transform function. (output)
+   * @param aResult The output matrix. (output)
+   * @return Whether the value was successfully parsed.
+   */
+  static bool ParseTransformIntoMatrix(const nsAString& aValue,
+                                       bool& aContains3DTransform,
+                                       RawGeckoGfxMatrix4x4& aResult);
+
+  /**
+   * Parse a font descriptor.
+   *
+   * @param aDescID The font descriptor id.
+   * @param aValue The specified value.
+   * @param aUrl The parser url extra data.
+   * @param aResult The parsed result. (output)
+   * @return Whether the value was successfully parsed.
+   */
+  static bool ParseFontDescriptor(nsCSSFontDesc aDescID,
+                                  const nsAString& aValue,
+                                  URLExtraData* aUrl,
+                                  nsCSSValue& aResult);
+
+  /**
+   * Parse a font shorthand for FontFaceSet matching, so we only care about
+   * FontFamily, FontStyle, FontStretch, and FontWeight.
+   *
+   * @param aValue The specified value.
+   * @param aUrl The parser url extra data.
+   * @param aList The parsed FontFamily list. (output)
+   * @param aStyle The parsed FontStyle. (output)
+   * @param aStretch The parsed FontStretch. (output)
+   * @param aWeight The parsed FontWeight. (output)
+   * @return Whether the value was successfully parsed.
+   */
+  static bool ParseFontShorthandForMatching(const nsAString& aValue,
+                                            URLExtraData* aUrl,
+                                            RefPtr<SharedFontList>& aList,
+                                            nsCSSValue& aStyle,
+                                            nsCSSValue& aStretch,
+                                            nsCSSValue& aWeight);
+
+  /**
+   * Get a URLExtraData from |nsIDocument|.
+   *
+   * @param aDocument The current document.
+   * @return The URLExtraData object.
+   */
+  static already_AddRefed<URLExtraData> GetURLExtraData(nsIDocument* aDocument);
+
+  /**
+   * Get a ParsingEnvironment from |nsIDocument|.
+   *
+   * @param aDocument The current document.
+   * @return The ParsingEnvironment object.
+   */
+  static ParsingEnvironment GetParsingEnvironment(nsIDocument* aDocument);
 };
 
 } // namespace mozilla
diff --git a/layout/style/StyleAnimationValue.cpp b/layout/style/StyleAnimationValue.cpp
index 4a3ea7fc013c..184a73912b7a 100644
--- a/layout/style/StyleAnimationValue.cpp
+++ b/layout/style/StyleAnimationValue.cpp
@@ -30,9 +30,9 @@
 #include "mozilla/css/Declaration.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/FloatingPoint.h"
-#include "mozilla/KeyframeUtils.h" // KeyframeUtils::ParseProperty
 #include "mozilla/Likely.h"
 #include "mozilla/ServoBindings.h" // RawServoDeclarationBlock
+#include "mozilla/ServoCSSParser.h"
 #include "gfxMatrix.h"
 #include "gfxQuaternion.h"
 #include "nsIDocument.h"
@@ -5477,7 +5477,8 @@ AnimationValue::FromString(nsCSSPropertyID aProperty,
     }
 
     RefPtr<RawServoDeclarationBlock> declarations =
-      KeyframeUtils::ParseProperty(aProperty, aValue, doc);
+      ServoCSSParser::ParseProperty(aProperty, aValue,
+                                    ServoCSSParser::GetParsingEnvironment(doc));
 
     if (!declarations) {
       return result;
diff --git a/layout/style/nsDOMCSSDeclaration.h b/layout/style/nsDOMCSSDeclaration.h
index 63633bfcaadf..5c19d59780e8 100644
--- a/layout/style/nsDOMCSSDeclaration.h
+++ b/layout/style/nsDOMCSSDeclaration.h
@@ -107,6 +107,31 @@ public:
 
   virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
 
+  // Information needed to parse a declaration for Servo side.
+  // Put this in public so other Servo parsing functions can reuse this.
+  struct MOZ_STACK_CLASS ServoCSSParsingEnvironment
+  {
+    RefPtr<mozilla::URLExtraData> mUrlExtraData;
+    nsCompatibility mCompatMode;
+    mozilla::css::Loader* mLoader;
+
+    ServoCSSParsingEnvironment(mozilla::URLExtraData* aUrlData,
+                               nsCompatibility aCompatMode,
+                               mozilla::css::Loader* aLoader)
+      : mUrlExtraData(aUrlData)
+      , mCompatMode(aCompatMode)
+      , mLoader(aLoader)
+    {}
+
+    ServoCSSParsingEnvironment(already_AddRefed<mozilla::URLExtraData> aUrlData,
+                               nsCompatibility aCompatMode,
+                               mozilla::css::Loader* aLoader)
+      : mUrlExtraData(aUrlData)
+      , mCompatMode(aCompatMode)
+      , mLoader(aLoader)
+    {}
+  };
+
 protected:
   // The reason for calling GetCSSDeclaration.
   enum Operation {
@@ -154,30 +179,6 @@ protected:
                                          "performance overhead (see bug 649163)") mCSSLoader;
   };
 
-  // Information neded to parse a declaration for Servo side.
-  struct MOZ_STACK_CLASS ServoCSSParsingEnvironment
-  {
-    RefPtr<mozilla::URLExtraData> mUrlExtraData;
-    nsCompatibility mCompatMode;
-    mozilla::css::Loader* mLoader;
-
-    ServoCSSParsingEnvironment(mozilla::URLExtraData* aUrlData,
-                               nsCompatibility aCompatMode,
-                               mozilla::css::Loader* aLoader)
-      : mUrlExtraData(aUrlData)
-      , mCompatMode(aCompatMode)
-      , mLoader(aLoader)
-    {}
-
-    ServoCSSParsingEnvironment(already_AddRefed<mozilla::URLExtraData> aUrlData,
-                               nsCompatibility aCompatMode,
-                               mozilla::css::Loader* aLoader)
-      : mUrlExtraData(aUrlData)
-      , mCompatMode(aCompatMode)
-      , mLoader(aLoader)
-    {}
-  };
-
   // On failure, mPrincipal should be set to null in aCSSParseEnv.
   // If mPrincipal is null, the other members may not be set to
   // anything meaningful.