diff --git a/lib/facter/resolvers/freebsd/system_memory.rb b/lib/facter/resolvers/freebsd/system_memory.rb
index 5c204617f9..25ba5c536c 100644
--- a/lib/facter/resolvers/freebsd/system_memory.rb
+++ b/lib/facter/resolvers/freebsd/system_memory.rb
@@ -15,25 +15,33 @@ def post_resolve(fact_name, _options)
 
           def calculate_system_memory(fact_name)
             read_total_memory_in_bytes
-            read_available_memory_in_bytes
+            read_used_memory_in_bytes
 
-            @fact_list[:used_bytes] = @fact_list[:total_bytes] - @fact_list[:available_bytes]
+            @fact_list[:available_bytes] = @fact_list[:total_bytes] - @fact_list[:used_bytes]
             @fact_list[:capacity] = Facter::Util::Resolvers::FilesystemHelper
                                     .compute_capacity(@fact_list[:used_bytes], @fact_list[:total_bytes])
 
             @fact_list[fact_name]
           end
 
-          def read_available_memory_in_bytes
-            output = Facter::Core::Execution.execute('vmstat -H --libxo json', logger: log)
-            data = JSON.parse(output)
-            @fact_list[:available_bytes] = data['memory']['free-memory'] * 1024
+          def pagesize
+            @pagesize ||= Facter::Freebsd::FfiHelper.sysctl_by_name(:long, 'vm.stats.vm.v_page_size')
+          end
+
+          def read_used_memory_in_bytes
+            require_relative 'ffi/ffi_helper'
+
+            @fact_list[:used_bytes] = pagesize * (
+              Facter::Freebsd::FfiHelper.sysctl_by_name(:long, 'vm.stats.vm.v_active_count') +
+              Facter::Freebsd::FfiHelper.sysctl_by_name(:long, 'vm.stats.vm.v_wire_count')
+            )
           end
 
           def read_total_memory_in_bytes
             require_relative 'ffi/ffi_helper'
 
-            @fact_list[:total_bytes] = Facter::Freebsd::FfiHelper.sysctl_by_name(:long, 'hw.physmem')
+            @fact_list[:total_bytes] = pagesize *
+                                       Facter::Freebsd::FfiHelper.sysctl_by_name(:long, 'vm.stats.vm.v_page_count')
           end
         end
       end
diff --git a/spec/facter/resolvers/freebsd/system_memory_spec.rb b/spec/facter/resolvers/freebsd/system_memory_spec.rb
index 0594a601f2..a95471ec13 100644
--- a/spec/facter/resolvers/freebsd/system_memory_spec.rb
+++ b/spec/facter/resolvers/freebsd/system_memory_spec.rb
@@ -12,12 +12,17 @@
   before do
     system_memory.instance_variable_set(:@log, log_spy)
     allow(Facter::Freebsd::FfiHelper).to receive(:sysctl_by_name)
-      .with(:long, 'hw.physmem')
-      .and_return(17_043_554_304)
-
-    allow(Facter::Core::Execution).to receive(:execute)
-      .with('vmstat -H --libxo json', { logger: log_spy })
-      .and_return(load_fixture('freebsd_vmstat').read)
+      .with(:long, 'vm.stats.vm.v_page_size')
+      .and_return(4096)
+    allow(Facter::Freebsd::FfiHelper).to receive(:sysctl_by_name)
+      .with(:long, 'vm.stats.vm.v_page_count')
+      .and_return(4_161_024)
+    allow(Facter::Freebsd::FfiHelper).to receive(:sysctl_by_name)
+      .with(:long, 'vm.stats.vm.v_active_count')
+      .and_return(2_335_139)
+    allow(Facter::Freebsd::FfiHelper).to receive(:sysctl_by_name)
+      .with(:long, 'vm.stats.vm.v_wire_count')
+      .and_return(1_167_569)
   end
 
   it 'returns available system memory in bytes' do
diff --git a/spec/fixtures/freebsd_vmstat b/spec/fixtures/freebsd_vmstat
deleted file mode 100644
index 01bcd3679a..0000000000
--- a/spec/fixtures/freebsd_vmstat
+++ /dev/null
@@ -1,6 +0,0 @@
-{"__version": "1", "processes": {"runnable":2,"waiting":14,"swapped-out":0}
-, "memory": {"available-memory":62672436,"free-memory":2633264,"total-page-faults":1972}
-, "paging-rates": {"page-reactivated":0,"paged-in":1,"paged-out":0,"freed":1831,"scanned":841}
-, "device": [{"name":"ad0","transfers":"0"}, {"name":"pa0","transfers":"0"}], "fault-rates": {"interrupts":3495,"system-calls":17391,"context-switches":11777}
-, "cpu-statistics": {"user":" 5","system":" 3","idle":"92"}
-}