diff --git a/libs/vkd3d-shader/ir.c b/libs/vkd3d-shader/ir.c
index a4a8f23b..b3f8ad85 100644
--- a/libs/vkd3d-shader/ir.c
+++ b/libs/vkd3d-shader/ir.c
@@ -6595,6 +6595,11 @@ static void vsir_validate_signature_element(struct validation_context *ctx,
         validator_error(ctx, VKD3D_SHADER_ERROR_VSIR_INVALID_SIGNATURE,
                 "element %u of %s signature: Invalid minimum precision %#x.",
                 idx, signature_type, element->min_precision);
+
+    if (element->interpolation_mode >= VKD3DSIM_COUNT)
+        validator_error(ctx, VKD3D_SHADER_ERROR_VSIR_INVALID_SIGNATURE,
+                "element %u of %s signature: Invalid interpolation mode %#x.",
+                idx, signature_type, element->interpolation_mode);
 }
 
 static void vsir_validate_signature(struct validation_context *ctx,