diff --git a/reactos/sdk/include/reactos/libs/libmpg123/compat.h b/reactos/sdk/include/reactos/libs/libmpg123/compat.h
index a993aa04cec..3cbc60d50a1 100644
--- a/reactos/sdk/include/reactos/libs/libmpg123/compat.h
+++ b/reactos/sdk/include/reactos/libs/libmpg123/compat.h
@@ -97,9 +97,11 @@
 
 typedef unsigned char byte;
 
+#ifndef __REACTOS__
 #ifdef _MSC_VER
 typedef long ssize_t;
 #endif
+#endif /* __REACTOS__ */
 
 /* A safe realloc also for very old systems where realloc(NULL, size) returns NULL. */
 void *safe_realloc(void *ptr, size_t size);
diff --git a/reactos/sdk/include/reactos/libs/libmpg123/config.h b/reactos/sdk/include/reactos/libs/libmpg123/config.h
index 97930c779f2..1abc53a6819 100644
--- a/reactos/sdk/include/reactos/libs/libmpg123/config.h
+++ b/reactos/sdk/include/reactos/libs/libmpg123/config.h
@@ -451,7 +451,7 @@
 /* #undef size_t */
 
 /* Define to `long' if <sys/types.h> does not define. */
-/* #undef ssize_t */
+#define ssize_t long
 
 /* Define to `unsigned short' if <sys/types.h> does not define. */
 /* #undef uint16_t */