--- a/gfx/thebes/gfxFcPlatformFontList.cpp
+++ b/gfx/thebes/gfxFcPlatformFontList.cpp
@@ -1061,16 +1061,20 @@ bool
 gfxFontconfigFontEntry::HasVariations()
 {
     if (mHasVariationsInitialized) {
         return mHasVariations;
     }
     mHasVariationsInitialized = true;
     mHasVariations = false;
 
+    if (!gfxPlatform::GetPlatform()->HasVariationFontSupport()) {
+        return mHasVariations;
+    }
+
     // For installed fonts, query the fontconfig pattern rather than paying
     // the cost of loading a FT_Face that we otherwise might never need.
     if (!IsUserFont() || IsLocalUserFont()) {
         FcBool variable;
         if ((FcPatternGetBool(mFontPattern, FC_VARIABLE, 0,
                               &variable) == FcResultMatch) && variable) {
             mHasVariations = true;
         }
@@ -1203,17 +1207,20 @@ gfxFontconfigFontFamily::FindStyleVariat
 
         // figure out the psname/fullname and choose which to use as the facename
         nsAutoString psname, fullname;
         GetFaceNames(face, mName, psname, fullname);
         const nsAutoString& faceName = !psname.IsEmpty() ? psname : fullname;
 
         gfxFontconfigFontEntry *fontEntry =
             new gfxFontconfigFontEntry(faceName, face, mContainsAppFonts);
-        fontEntry->SetupVariationRanges();
+
+        if (gfxPlatform::GetPlatform()->HasVariationFontSupport()) {
+            fontEntry->SetupVariationRanges();
+        }
 
         AddFontEntry(fontEntry);
 
         if (fontEntry->IsNormalStyle()) {
             numRegularFaces++;
         }
 
         if (LOG_FONTLIST_ENABLED()) {

--- a/gfx/thebes/gfxFontEntry.cpp
+++ b/gfx/thebes/gfxFontEntry.cpp
@@ -1030,17 +1030,18 @@ gfxFontEntry::GetColorLayersInfo(uint32_
                                              aDefaultColor,
                                              aLayerGlyphs,
                                              aLayerColors);
 }
 
 void
 gfxFontEntry::SetupVariationRanges()
 {
-    if (!HasVariations() || IsUserFont()) {
+    if (!gfxPlatform::GetPlatform()->HasVariationFontSupport() ||
+        !HasVariations() || IsUserFont()) {
         return;
     }
     AutoTArray<gfxFontVariationAxis,4> axes;
     GetVariationAxes(axes);
     for (const auto& axis : axes) {
         switch (axis.mTag) {
         case HB_TAG('w','g','h','t'):
             // If the axis range looks like it doesn't fit the CSS font-weight
@@ -1092,16 +1093,20 @@ gfxFontEntry::SetupVariationRanges()
         }
     }
 }
 
 void
 gfxFontEntry::GetVariationsForStyle(nsTArray<gfxFontVariation>& aResult,
                                     const gfxFontStyle& aStyle)
 {
+    if (!gfxPlatform::GetPlatform()->HasVariationFontSupport()) {
+        return;
+    }
+
     // Resolve high-level CSS properties from the requested style
     // (font-{style,weight,stretch}) to the appropriate variations.
     float clampedWeight = Weight().Clamp(aStyle.weight).ToFloat();
     aResult.AppendElement(gfxFontVariation{HB_TAG('w','g','h','t'),
                                            clampedWeight});
 
     float clampedStretch = Stretch().Clamp(aStyle.stretch).Percentage();
     aResult.AppendElement(gfxFontVariation{HB_TAG('w','d','t','h'),

--- a/gfx/thebes/gfxMacPlatformFontList.mm
+++ b/gfx/thebes/gfxMacPlatformFontList.mm
@@ -283,17 +283,19 @@ MacOSFontEntry::CreateFontInstance(const
     return new gfxMacFont(unscaledFont, this, aFontStyle, aNeedsBold);
 }
 
 bool
 MacOSFontEntry::HasVariations()
 {
     if (!mHasVariationsInitialized) {
         mHasVariationsInitialized = true;
-        mHasVariations = HasFontTable(TRUETYPE_TAG('f','v','a','r'));
+        mHasVariations =
+            gfxPlatform::GetPlatform()->HasVariationFontSupport() &&
+            HasFontTable(TRUETYPE_TAG('f','v','a','r'));
     }
 
     return mHasVariations;
 }
 
 void
 MacOSFontEntry::GetVariationAxes(nsTArray<gfxFontVariationAxis>& aVariationAxes)
 {
@@ -924,17 +926,19 @@ gfxMacFontFamily::FindStyleVariations(Fo
             [facename hasSuffix:@"Oblique"])
         {
             fontEntry->mStyleRange = SlantStyleRange(FontSlantStyle::Italic());
         }
         if (macTraits & NSFixedPitchFontMask) {
             fontEntry->mFixedPitch = true;
         }
 
-        fontEntry->SetupVariationRanges();
+        if (gfxPlatform::GetPlatform()->HasVariationFontSupport()) {
+            fontEntry->SetupVariationRanges();
+        }
 
         if (LOG_FONTLIST_ENABLED()) {
             nsAutoCString weightString;
             fontEntry->Weight().ToString(weightString);
             nsAutoCString stretchString;
             fontEntry->Stretch().ToString(stretchString);
             LOG_FONTLIST(("(fontlist) added (%s) to family (%s)"
                  " with style: %s weight: %s stretch: %s"

--- a/gfx/thebes/gfxPlatform.cpp
+++ b/gfx/thebes/gfxPlatform.cpp
@@ -773,16 +773,19 @@ gfxPlatform::Init()
 
     gPlatform->PopulateScreenInfo();
     gPlatform->ComputeTileSize();
 
 #ifdef MOZ_ENABLE_FREETYPE
     Factory::SetFTLibrary(gPlatform->GetFTLibrary());
 #endif
 
+    gPlatform->mHasVariationFontSupport =
+        gPlatform->CheckVariationFontSupport();
+
     nsresult rv;
     rv = gfxPlatformFontList::Init();
     if (NS_FAILED(rv)) {
         MOZ_CRASH("Could not initialize gfxPlatformFontList");
     }
 
     gPlatform->mScreenReferenceSurface =
         gPlatform->CreateOffscreenSurface(IntSize(1, 1),
@@ -846,17 +849,17 @@ gfxPlatform::Init()
 #endif
 
     InitNullMetadata();
     InitOpenGLConfig();
 
     if (XRE_IsParentProcess()) {
       gfxVars::SetDXInterop2Blocked(IsDXInterop2Blocked());
       Preferences::Unlock(FONT_VARIATIONS_PREF);
-      if (!gPlatform->CheckVariationFontSupport()) {
+      if (!gPlatform->HasVariationFontSupport()) {
         // Ensure variation fonts are disabled and the pref is locked.
         Preferences::SetBool(FONT_VARIATIONS_PREF, false,
                              PrefValueKind::Default);
         Preferences::SetBool(FONT_VARIATIONS_PREF, false);
         Preferences::Lock(FONT_VARIATIONS_PREF);
       }
     }
 

--- a/gfx/thebes/gfxPlatform.h
+++ b/gfx/thebes/gfxPlatform.h
@@ -719,16 +719,20 @@ public:
      * GPUProcessManager, in the UI process.
      */
     virtual void ImportGPUDeviceData(const mozilla::gfx::GPUDeviceData& aData);
 
     virtual FT_Library GetFTLibrary() {
       return nullptr;
     }
 
+    bool HasVariationFontSupport() const {
+      return mHasVariationFontSupport;
+    }
+
     // you probably want to use gfxVars::UseWebRender() instead of this
     static bool WebRenderPrefEnabled();
     // you probably want to use gfxVars::UseWebRender() instead of this
     static bool WebRenderEnvvarEnabled();
 
 protected:
     gfxPlatform();
     virtual ~gfxPlatform();
@@ -809,16 +813,19 @@ protected:
     int8_t  mOpenTypeSVGEnabled;
 
     int8_t  mBidiNumeralOption;
 
     // whether to always search font cmaps globally
     // when doing system font fallback
     int8_t  mFallbackUsesCmaps;
 
+    // Whether the platform supports rendering OpenType font variations
+    bool    mHasVariationFontSupport;
+
     // max character limit for words in word cache
     int32_t mWordCacheCharLimit;
 
     // max number of entries in word cache
     int32_t mWordCacheMaxEntries;
 
     uint64_t mTotalSystemMemory;
 

--- a/gfx/thebes/gfxPlatformMac.cpp
+++ b/gfx/thebes/gfxPlatformMac.cpp
@@ -634,13 +634,14 @@ gfxPlatformMac::GetPlatformCMSOutputProf
     }
 
     ::CFRelease(iccp);
 }
 
 bool
 gfxPlatformMac::CheckVariationFontSupport()
 {
-    // We don't allow variation fonts to be enabled before 10.12,
+    // We don't allow variation fonts to be enabled before 10.13,
     // as although the Core Text APIs existed, they are known to be
     // fairly buggy.
-    return nsCocoaFeatures::OnSierraOrLater();
+    // (Note that Safari also requires 10.13 for variation-font support.)
+    return nsCocoaFeatures::OnHighSierraOrLater();
 }