diff --git a/src/os/netware/netware_sigar.c b/src/os/netware/netware_sigar.c
index 53c1b3bc..4423eca7 100644
--- a/src/os/netware/netware_sigar.c
+++ b/src/os/netware/netware_sigar.c
@@ -32,7 +32,7 @@ int sigar_mem_get(sigar_t *sigar, sigar_mem_t *mem)
     }
     mem->total  = info.TotalKnownSystemMemoryUnder4Gb;
     mem->used   = info.TotalWorkMemory;
-    mem->free   = mem->total - mem->free;
+    mem->free   = mem->total - mem->used;
     mem->shared = -1;
     mem->actual_free = mem->free;
     mem->actual_used = mem->used;