diff --git a/src/winml/modelkit/commands/compile.py b/src/winml/modelkit/commands/compile.py
index eb849d044..818a99771 100644
--- a/src/winml/modelkit/commands/compile.py
+++ b/src/winml/modelkit/commands/compile.py
@@ -26,6 +26,7 @@
 from rich.console import Console
 
 from ..config.precision import _DEVICE_TO_PROVIDER, VALID_EPS
+from ..onnx import is_compiled_onnx
 from ..utils.logging import configure_logging
 
 
@@ -159,6 +160,12 @@ def compile(
     if model is None:
         raise click.UsageError("Missing option '--model' / '-m'.")
 
+    if is_compiled_onnx(model):
+        raise click.ClickException(
+            f"{model} is already a compiled EPContext model and cannot be re-compiled. "
+            "Run 'winml compile' on the original ONNX model."
+        )
+
     # Import compiler (late import to speed up CLI)
     from ..compiler import WinMLCompileConfig, compile_onnx
 
diff --git a/src/winml/modelkit/commands/optimize.py b/src/winml/modelkit/commands/optimize.py
index c1f704da7..7e410760a 100644
--- a/src/winml/modelkit/commands/optimize.py
+++ b/src/winml/modelkit/commands/optimize.py
@@ -30,7 +30,7 @@
 import click
 from rich.console import Console
 
-from ..onnx import load_onnx, save_onnx
+from ..onnx import is_compiled_onnx, load_onnx, save_onnx
 
 
 if TYPE_CHECKING:
@@ -382,6 +382,12 @@ def optimize(
     if model is None:
         raise click.UsageError("Missing option '--model' / '-m'.")
 
+    if is_compiled_onnx(model):
+        raise click.ClickException(
+            f"{model} is a compiled EPContext model and cannot be optimized. "
+            "Run 'winml optimize' on the original ONNX model before compilation."
+        )
+
     # Inherit debug mode from parent
     if ctx.obj and ctx.obj.get("debug"):
         verbose = True
diff --git a/src/winml/modelkit/commands/quantize.py b/src/winml/modelkit/commands/quantize.py
index 5437837eb..5dae75b4b 100644
--- a/src/winml/modelkit/commands/quantize.py
+++ b/src/winml/modelkit/commands/quantize.py
@@ -25,6 +25,7 @@
 import click
 from rich.console import Console
 
+from ..onnx import is_compiled_onnx
 from ..utils.logging import configure_logging
 
 
@@ -141,6 +142,12 @@ def quantize(
 
     configure_logging(verbose=verbose)
 
+    if is_compiled_onnx(model):
+        raise click.ClickException(
+            f"{model} is a compiled EPContext model and cannot be quantized. "
+            "Run 'winml quantize' on the original ONNX model before compilation."
+        )
+
     # Import quantizer (late import to speed up CLI)
     from ..quant import WinMLQuantizationConfig, quantize_onnx