diff --git a/src/os/win32/sigar_os.h b/src/os/win32/sigar_os.h
index f9bf2e72..a3a50a82 100644
--- a/src/os/win32/sigar_os.h
+++ b/src/os/win32/sigar_os.h
@@ -204,6 +204,9 @@ typedef struct {
 } MIB_UDPEXTABLE, *PMIB_UDPEXTABLE;
 
 /* end undocumented structures */
+
+typedef BOOL (CALLBACK *LPCONVERTSTRINGSID)(LPCSTR, PSID *);
+
 typedef DWORD (CALLBACK *LPGETIPFORWARDTABLE)(PMIB_IPFORWARDTABLE, PULONG, BOOL);
 
 typedef DWORD (CALLBACK *LPGETIFTABLE)(PMIB_IFTABLE, PULONG, BOOL);
@@ -279,11 +282,13 @@ struct sigar_t {
     HKEY handle;
     char *perfbuf;
     DWORD perfbuf_size;
+    HINSTANCE adv_handle;
     HINSTANCE ip_handle;
     HINSTANCE nt_handle;
     HINSTANCE ps_handle;
     HINSTANCE wts_handle;
     HINSTANCE sta_handle;
+    LPCONVERTSTRINGSID convert_string_sid;
     LPGETIFTABLE get_if_table;
     LPGETIPFORWARDTABLE get_ipforward_table;
     LPGETTCPTABLE get_tcp_table;
diff --git a/src/os/win32/win32_sigar.c b/src/os/win32/win32_sigar.c
index 9ce3aa02..df42d6ee 100644
--- a/src/os/win32/win32_sigar.c
+++ b/src/os/win32/win32_sigar.c
@@ -258,6 +258,17 @@ int sigar_os_open(sigar_t **sigar)
         (*sigar)->ip_handle = NULL;
     }
 
+    if ((h = LoadLibrary("advapi32.dll"))) {
+        (*sigar)->convert_string_sid =
+            (LPCONVERTSTRINGSID)GetProcAddress(h, 
+                                               "ConvertStringSidToSidA");
+        (*sigar)->adv_handle = h;
+    }
+    else {
+        (*sigar)->adv_handle = NULL;
+        (*sigar)->convert_string_sid = NULL;
+    }
+
     if ((h = LoadLibrary("Ntdll.dll"))) {
         (*sigar)->get_ntsys_info =
             (LPSYSINFO)GetProcAddress(h, "NtQuerySystemInformation");
@@ -2212,15 +2223,16 @@ static int get_logon_info(HKEY users,
     return SIGAR_OK;
 }
 
-/*XXX dlload, not in NT */
-BOOL WINAPI ConvertStringSidToSidA(LPCSTR, PSID *);
-
 static int sigar_who_registry(sigar_t *sigar,
                               sigar_who_list_t *wholist)
 {
     HKEY users;
     DWORD index=0, status;
 
+    if (!sigar->convert_string_sid) {
+        return ENOENT;
+    }
+
     status = RegOpenKey(HKEY_USERS, NULL, &users);
     if (status != ERROR_SUCCESS) {
         return status;
@@ -2249,7 +2261,7 @@ static int sigar_who_registry(sigar_t *sigar,
             continue;
         }
 
-        if (!ConvertStringSidToSidA(subkey, &sid)) {
+        if (!sigar->convert_string_sid(subkey, &sid)) {
             continue;
         }