diff --git a/libs/vkd3d-shader/ir.c b/libs/vkd3d-shader/ir.c
index 6c0964cc..9ee38ffe 100644
--- a/libs/vkd3d-shader/ir.c
+++ b/libs/vkd3d-shader/ir.c
@@ -1364,6 +1364,14 @@ static void vsir_validate_src_param(struct validation_context *ctx,
         const struct vkd3d_shader_src_param *src)
 {
     vsir_validate_register(ctx, &src->reg);
+
+    if (src->swizzle & ~0x03030303u)
+        validator_error(ctx, VKD3D_SHADER_ERROR_VSIR_INVALID_SWIZZLE, "Source has invalid swizzle %#x.",
+                src->swizzle);
+
+    if (src->modifiers >= VKD3DSPSM_COUNT)
+        validator_error(ctx, VKD3D_SHADER_ERROR_VSIR_INVALID_MODIFIERS, "Source has invalid modifiers %#x.",
+                src->modifiers);
 }
 
 static void vsir_validate_instruction(struct validation_context *ctx)
diff --git a/libs/vkd3d-shader/vkd3d_shader_private.h b/libs/vkd3d-shader/vkd3d_shader_private.h
index 85a1d201..5fd93091 100644
--- a/libs/vkd3d-shader/vkd3d_shader_private.h
+++ b/libs/vkd3d-shader/vkd3d_shader_private.h
@@ -188,6 +188,7 @@ enum vkd3d_shader_error
     VKD3D_SHADER_ERROR_VSIR_INVALID_WRITE_MASK          = 9003,
     VKD3D_SHADER_ERROR_VSIR_INVALID_MODIFIERS           = 9004,
     VKD3D_SHADER_ERROR_VSIR_INVALID_SHIFT               = 9005,
+    VKD3D_SHADER_ERROR_VSIR_INVALID_SWIZZLE             = 9006,
 };
 
 enum vkd3d_shader_opcode
@@ -590,6 +591,7 @@ enum vkd3d_shader_src_modifier
     VKD3DSPSM_ABS = 11,
     VKD3DSPSM_ABSNEG = 12,
     VKD3DSPSM_NOT = 13,
+    VKD3DSPSM_COUNT,
 };
 
 #define VKD3DSP_WRITEMASK_0   0x1u /* .x r */