diff --git a/StandAlone/StandAlone.cpp b/StandAlone/StandAlone.cpp
index 598ca9ad..e038ed16 100644
--- a/StandAlone/StandAlone.cpp
+++ b/StandAlone/StandAlone.cpp
@@ -1924,7 +1924,8 @@ void usage()
            "  -Od         disables optimization; may cause illegal SPIR-V for HLSL\n"
            "  -Os         optimizes SPIR-V to minimize size\n"
            "  -P<text> | --preamble-text <text> | --P <text>\n"
-           "              inject custom preamble text\n"
+           "              inject custom preamble text, which is treated as if it\n"
+           "              appeared immediately after the version declaration (if any).\n"
            "  -R          use relaxed verification rules for generating Vulkan SPIR-V,\n"
            "              allowing the use of default uniforms, atomic_uints, and\n"
            "              gl_VertexID and gl_InstanceID keywords.\n"