diff --git a/tools/file_operations.py b/tools/file_operations.py
index d217d54a9a..0cf1105310 100644
--- a/tools/file_operations.py
+++ b/tools/file_operations.py
@@ -441,8 +441,8 @@ class ShellFileOperations(FileOperations):
         # Clamp limit
         limit = min(limit, MAX_LINES)
         
-        # Check if file exists and get metadata
-        stat_cmd = f"stat -c '%s' {self._escape_shell_arg(path)} 2>/dev/null"
+        # Check if file exists and get size (wc -c is POSIX, works on Linux + macOS)
+        stat_cmd = f"wc -c < {self._escape_shell_arg(path)} 2>/dev/null"
         stat_result = self._exec(stat_cmd)
         
         if stat_result.exit_code != 0:
@@ -518,8 +518,8 @@ class ShellFileOperations(FileOperations):
 
     def _read_image(self, path: str) -> ReadResult:
         """Read an image file, returning base64 content."""
-        # Get file size
-        stat_cmd = f"stat -c '%s' {self._escape_shell_arg(path)} 2>/dev/null"
+        # Get file size (wc -c is POSIX, works on Linux + macOS)
+        stat_cmd = f"wc -c < {self._escape_shell_arg(path)} 2>/dev/null"
         stat_result = self._exec(stat_cmd)
         try:
             file_size = int(stat_result.stdout.strip())
@@ -648,8 +648,8 @@ class ShellFileOperations(FileOperations):
         if write_result.exit_code != 0:
             return WriteResult(error=f"Failed to write file: {write_result.stdout}")
         
-        # Get bytes written
-        stat_cmd = f"stat -c '%s' {self._escape_shell_arg(path)} 2>/dev/null"
+        # Get bytes written (wc -c is POSIX, works on Linux + macOS)
+        stat_cmd = f"wc -c < {self._escape_shell_arg(path)} 2>/dev/null"
         stat_result = self._exec(stat_cmd)
         
         try: