diff --git a/src/physfs_internal.h b/src/physfs_internal.h
index 27082e7..56a2e49 100644
--- a/src/physfs_internal.h
+++ b/src/physfs_internal.h
@@ -30,7 +30,7 @@
 #include <malloc.h>
 #endif
 
-#if defined(__sun) || defined(sun)
+#if PHYSFS_PLATFORM_SOLARIS
 #include <alloca.h>
 #endif