diff --git a/libs/vkd3d-shader/preproc.y b/libs/vkd3d-shader/preproc.y
index ac6f6479..3f02ac03 100644
--- a/libs/vkd3d-shader/preproc.y
+++ b/libs/vkd3d-shader/preproc.y
@@ -48,6 +48,10 @@ int preproc_yylex(PREPROC_YYSTYPE *yylval_param, PREPROC_YYLTYPE *yylloc_param,
 
 #define YYLLOC_DEFAULT(cur, rhs, n) (cur) = YYRHSLOC(rhs, !!n)
 
+#ifndef S_ISREG
+# define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
+#endif
+
 static void preproc_error(struct preproc_ctx *ctx, const struct vkd3d_shader_location *loc,
         enum vkd3d_shader_error error, const char *format, ...)
 {