diff --git a/src/Ultra.Sampler/MacOS/MacOSLibSystem.cs b/src/Ultra.Sampler/MacOS/MacOSLibSystem.cs
index 40ed80b..b2fc3e4 100644
--- a/src/Ultra.Sampler/MacOS/MacOSLibSystem.cs
+++ b/src/Ultra.Sampler/MacOS/MacOSLibSystem.cs
@@ -22,6 +22,8 @@ internal static partial class MacOSLibSystem
     public const int KERN_INVALID_ADDRESS = 1;
 
     public const int PROT_READ = 0x01;
+    public const int PROT_WRITE = 0x02;
+    public const int PROT_EXEC = 0x04;
 
     public const int PT_ATTACH = 10; // TODO: deprecated
     public const int PT_DETACH = 11;
diff --git a/src/Ultra.Sampler/MacOS/MacOSUltraSampler.cs b/src/Ultra.Sampler/MacOS/MacOSUltraSampler.cs
index 1f1d96c..f210b66 100644
--- a/src/Ultra.Sampler/MacOS/MacOSUltraSampler.cs
+++ b/src/Ultra.Sampler/MacOS/MacOSUltraSampler.cs
@@ -236,7 +236,7 @@ private static ulong GetDyldCodeSize(nint headerPtr)
             if (command.cmd == MacOSLibSystem.LC_SEGMENT_64)
             {
                 ref var segment = ref Unsafe.As<MacOSLibSystem.load_command,MacOSLibSystem.segment_command_64>(ref command);
-                if (segment.vmaddr < startAddress)
+                if ((segment.initprot & MacOSLibSystem.PROT_EXEC) != 0  && segment.vmaddr < startAddress)
                 {
                     startAddress = segment.vmaddr;
                 }
@@ -253,7 +253,7 @@ private static ulong GetDyldCodeSize(nint headerPtr)
                 ref var segment = ref Unsafe.As<MacOSLibSystem.load_command, MacOSLibSystem.segment_command_64>(ref command);
 
                 var newSize = (ulong)((long)segment.vmaddr + (long)segment.vmsize - (long)startAddress);
-                if (newSize > size)
+                if ((segment.initprot & MacOSLibSystem.PROT_EXEC) != 0 && newSize > size)
                 {
                     size = newSize;
                 }