diff --git a/Library/Homebrew/extend/os/mac/hardware/cpu.rb b/Library/Homebrew/extend/os/mac/hardware/cpu.rb
index ca9cded68d..96c6fb6fb4 100644
--- a/Library/Homebrew/extend/os/mac/hardware/cpu.rb
+++ b/Library/Homebrew/extend/os/mac/hardware/cpu.rb
@@ -22,33 +22,10 @@ module Hardware
       end
 
       def family
-        case sysctl_int("hw.cpufamily")
-        when 0x73d67300 # Yonah: Core Solo/Duo
-          :core
-        when 0x426f69ef # Merom: Core 2 Duo
-          :core2
-        when 0x78ea4fbc # Penryn
-          :penryn
-        when 0x6b5a4cd2 # Nehalem
-          :nehalem
-        when 0x573B5EEC # Arrandale
-          :arrandale
-        when 0x5490B78C # Sandy Bridge
-          :sandybridge
-        when 0x1F65E835 # Ivy Bridge
-          :ivybridge
-        when 0x10B282DC # Haswell
-          :haswell
-        when 0x582ed09c # Broadwell
-          :broadwell
-        when 0x37fc219f # Skylake
-          :skylake
-        when 0x0f817246 # Kaby Lake
-          :kabylake
-        when 0x38435547 # Ice Lake
-          :icelake
-        when 0x07d34b9f # ARMv8.3-A (Vortex, Tempest)
-          :arm_vortex_tempest
+        if arm?
+          arm_family
+        elsif intel?
+          intel_family
         else
           :dunno
         end
@@ -124,6 +101,48 @@ module Hardware
 
       private
 
+      def arm_family
+        case sysctl_int("hw.cpufamily")
+        when 0x07d34b9f             # ARMv8.3-A (Vortex, Tempest)
+          :arm_vortex_tempest
+        when 0x573b5eec, 0x1b588bb3 # ARMv8.4-A (Firestorm, Icestorm)
+          :arm_firestorm_icestorm
+        else
+          :dunno
+        end
+      end
+
+      def intel_family
+        case sysctl_int("hw.cpufamily")
+        when 0x73d67300 # Yonah: Core Solo/Duo
+          :core
+        when 0x426f69ef # Merom: Core 2 Duo
+          :core2
+        when 0x78ea4fbc # Penryn
+          :penryn
+        when 0x6b5a4cd2 # Nehalem
+          :nehalem
+        when 0x573b5eec # Arrandale
+          :arrandale
+        when 0x5490b78c # Sandy Bridge
+          :sandybridge
+        when 0x1f65e835 # Ivy Bridge
+          :ivybridge
+        when 0x10b282dc # Haswell
+          :haswell
+        when 0x582ed09c # Broadwell
+          :broadwell
+        when 0x37fc219f # Skylake
+          :skylake
+        when 0x0f817246 # Kaby Lake
+          :kabylake
+        when 0x38435547 # Ice Lake
+          :icelake
+        else
+          :dunno
+        end
+      end
+
       def sysctl_bool(key)
         sysctl_int(key) == 1
       end
diff --git a/Library/Homebrew/test/hardware/cpu_spec.rb b/Library/Homebrew/test/hardware/cpu_spec.rb
index adace43ae9..75d336e7d8 100644
--- a/Library/Homebrew/test/hardware/cpu_spec.rb
+++ b/Library/Homebrew/test/hardware/cpu_spec.rb
@@ -22,6 +22,7 @@ describe Hardware::CPU do
   describe "::family" do
     let(:cpu_families) {
       [
+        :arm_firestorm_icestorm,
         :arm_vortex_tempest,
         :arrandale,
         :atom,
@@ -48,5 +49,28 @@ describe Hardware::CPU do
     it "returns the current CPU's family name as a symbol, or :dunno if it cannot be detected" do
       expect(cpu_families).to include described_class.family
     end
+
+    context "when hw.cpufamily is 0x573b5eec on a Mac", :needs_macos do
+      before do
+        allow(described_class)
+          .to receive(:sysctl_int)
+          .with("hw.cpufamily")
+          .and_return(0x573b5eec)
+      end
+
+      it "returns :arm_firestorm_icestorm on ARM" do
+        allow(described_class).to receive(:arm?).and_return(true)
+        allow(described_class).to receive(:intel?).and_return(false)
+
+        expect(described_class.family).to eq(:arm_firestorm_icestorm)
+      end
+
+      it "returns :westmere on Intel" do
+        allow(described_class).to receive(:arm?).and_return(false)
+        allow(described_class).to receive(:intel?).and_return(true)
+
+        expect(described_class.family).to eq(:westmere)
+      end
+    end
   end
 end