diff --git a/dlls/advapi32/advapi32_misc.h b/dlls/advapi32/advapi32_misc.h
index 4ced1e8a648..be3873a4b4d 100644
--- a/dlls/advapi32/advapi32_misc.h
+++ b/dlls/advapi32/advapi32_misc.h
@@ -25,6 +25,8 @@
 #include "winnls.h"
 #include "wine/heap.h"
 
+#define ARRAY_SIZE(array) (sizeof(array) / sizeof((array)[0]))
+
 const char * debugstr_sid(PSID sid) DECLSPEC_HIDDEN;
 BOOL ADVAPI_IsLocalComputer(LPCWSTR ServerName) DECLSPEC_HIDDEN;
 BOOL ADVAPI_GetComputerSid(PSID sid) DECLSPEC_HIDDEN;
diff --git a/dlls/advapi32/cred.c b/dlls/advapi32/cred.c
index df4142113c4..49a1c34d1cc 100644
--- a/dlls/advapi32/cred.c
+++ b/dlls/advapi32/cred.c
@@ -248,7 +248,7 @@ static DWORD mac_read_credential_from_item(SecKeychainItemRef item, BOOL require
     SecKeychainAttributeList *attr_list;
     UInt32 info_tags[] = { kSecServiceItemAttr, kSecAccountItemAttr,
                            kSecCommentItemAttr, kSecCreationDateItemAttr };
-    info.count = sizeof(info_tags)/sizeof(info_tags[0]);
+    info.count = ARRAY_SIZE(info_tags);
     info.tag = info_tags;
     info.format = NULL;
     status = SecKeychainItemCopyAttributesAndData(item, &info, NULL, &attr_list, &cred_blob_len, &cred_blob);
@@ -641,12 +641,12 @@ static LPWSTR get_key_name_for_target(LPCWSTR target_name, DWORD type)
     if (type == CRED_TYPE_GENERIC)
     {
         prefix = wszGenericPrefix;
-        len += sizeof(wszGenericPrefix)/sizeof(wszGenericPrefix[0]);
+        len += ARRAY_SIZE(wszGenericPrefix);
     }
     else
     {
         prefix = wszDomPasswdPrefix;
-        len += sizeof(wszDomPasswdPrefix)/sizeof(wszDomPasswdPrefix[0]);
+        len += ARRAY_SIZE(wszDomPasswdPrefix);
     }
 
     key_name = heap_alloc(len * sizeof(WCHAR));
@@ -792,7 +792,7 @@ static DWORD mac_enumerate_credentials(LPCWSTR filter, PCREDENTIALW *credentials
             UInt32 info_tags[] = { kSecServiceItemAttr };
             BOOL match;
 
-            info.count = sizeof(info_tags)/sizeof(info_tags[0]);
+            info.count = ARRAY_SIZE(info_tags);
             info.tag = info_tags;
             info.format = NULL;
             status = SecKeychainItemCopyAttributesAndData(item, &info, NULL, &attr_list, NULL, NULL);
@@ -851,7 +851,7 @@ static DWORD mac_delete_credential(LPCWSTR TargetName)
             UInt32 info_tags[] = { kSecServiceItemAttr };
             LPWSTR target_name;
             INT str_len;
-            info.count = sizeof(info_tags)/sizeof(info_tags[0]);
+            info.count = ARRAY_SIZE(info_tags);
             info.tag = info_tags;
             info.format = NULL;
             status = SecKeychainItemCopyAttributesAndData(item, &info, NULL, &attr_list, NULL, NULL);
@@ -1439,7 +1439,7 @@ BOOL WINAPI CredReadW(LPCWSTR TargetName, DWORD Type, DWORD Flags, PCREDENTIALW
                 UInt32 info_tags[] = { kSecServiceItemAttr };
                 LPWSTR target_name;
                 INT str_len;
-                info.count = sizeof(info_tags)/sizeof(info_tags[0]);
+                info.count = ARRAY_SIZE(info_tags);
                 info.tag = info_tags;
                 info.format = NULL;
                 status = SecKeychainItemCopyAttributesAndData(item, &info, NULL, &attr_list, NULL, NULL);
diff --git a/dlls/advapi32/registry.c b/dlls/advapi32/registry.c
index 7a26fffc55e..44b4bedb07d 100644
--- a/dlls/advapi32/registry.c
+++ b/dlls/advapi32/registry.c
@@ -84,9 +84,7 @@ static const WCHAR * const root_key_names[] =
     name_DYN_DATA
 };
 
-#define NB_SPECIAL_ROOT_KEYS   (sizeof(root_key_names)/sizeof(root_key_names[0]))
-
-static HKEY special_root_keys[NB_SPECIAL_ROOT_KEYS];
+static HKEY special_root_keys[ARRAY_SIZE(root_key_names)];
 static BOOL hkcu_cache_disabled;
 
 static const BOOL is_win64 = (sizeof(void *) > sizeof(int));
diff --git a/dlls/advapi32/security.c b/dlls/advapi32/security.c
index 6f4fb44ae95..f081b6b803f 100644
--- a/dlls/advapi32/security.c
+++ b/dlls/advapi32/security.c
@@ -964,7 +964,7 @@ CreateWellKnownSid( WELL_KNOWN_SID_TYPE WellKnownSidType,
         return FALSE;
     }
 
-    for (i = 0; i < sizeof(WellKnownSids)/sizeof(WellKnownSids[0]); i++) {
+    for (i = 0; i < ARRAY_SIZE(WellKnownSids); i++) {
         if (WellKnownSids[i].Type == WellKnownSidType) {
             DWORD length = GetSidLengthRequired(WellKnownSids[i].Sid.SubAuthorityCount);
 
@@ -991,7 +991,7 @@ CreateWellKnownSid( WELL_KNOWN_SID_TYPE WellKnownSidType,
         return FALSE;
     }
 
-    for (i = 0; i < sizeof(WellKnownRids)/sizeof(WellKnownRids[0]); i++)
+    for (i = 0; i < ARRAY_SIZE(WellKnownRids); i++)
         if (WellKnownRids[i].Type == WellKnownSidType) {
             UCHAR domain_subauth = *GetSidSubAuthorityCount(DomainSid);
             DWORD domain_sid_length = GetSidLengthRequired(domain_subauth);
@@ -1028,7 +1028,7 @@ IsWellKnownSid( PSID pSid, WELL_KNOWN_SID_TYPE WellKnownSidType )
     unsigned int i;
     TRACE("(%s, %d)\n", debugstr_sid(pSid), WellKnownSidType);
 
-    for (i = 0; i < sizeof(WellKnownSids)/sizeof(WellKnownSids[0]); i++)
+    for (i = 0; i < ARRAY_SIZE(WellKnownSids); i++)
         if (WellKnownSids[i].Type == WellKnownSidType)
             if (EqualSid(pSid, (PSID)&(WellKnownSids[i].Sid.Revision)))
                 return TRUE;
@@ -2252,7 +2252,7 @@ LookupAccountSidW(
     /* check the well known SIDs first */
     for (i = 0; i <= WinAccountProtectedUsersSid; i++) {
         if (IsWellKnownSid(sid, i)) {
-            for (j = 0; j < (sizeof(ACCOUNT_SIDS) / sizeof(ACCOUNT_SIDS[0])); j++) {
+            for (j = 0; j < ARRAY_SIZE(ACCOUNT_SIDS); j++) {
                 if (ACCOUNT_SIDS[j].type == i) {
                     ac = ACCOUNT_SIDS[j].account;
                     dm = ACCOUNT_SIDS[j].domain;
@@ -2937,7 +2937,7 @@ BOOL lookup_local_wellknown_name( const LSA_UNICODE_STRING *account_and_domain,
     *handled = FALSE;
     split_domain_account( account_and_domain, &account, &domain );
 
-    for (i = 0; i < sizeof(ACCOUNT_SIDS) / sizeof(ACCOUNT_SIDS[0]); i++)
+    for (i = 0; i < ARRAY_SIZE(ACCOUNT_SIDS); i++)
     {
         /* check domain first */
         if (domain.Buffer && !match_domain( i, &domain )) continue;
@@ -4926,7 +4926,7 @@ static BOOL DumpSidNumeric(PSID psid, WCHAR **pwptr, ULONG *plen)
 static BOOL DumpSid(PSID psid, WCHAR **pwptr, ULONG *plen)
 {
     size_t i;
-    for (i = 0; i < sizeof(WellKnownSids) / sizeof(WellKnownSids[0]); i++)
+    for (i = 0; i < ARRAY_SIZE(WellKnownSids); i++)
     {
         if (WellKnownSids[i].wstr[0] && EqualSid(psid, (PSID)&(WellKnownSids[i].Sid.Revision)))
         {
@@ -4983,7 +4983,7 @@ static void DumpRights(DWORD mask, WCHAR **pwptr, ULONG *plen)
         return;
 
     /* first check if the right have name */
-    for (i = 0; i < sizeof(AceRights)/sizeof(AceRights[0]); i++)
+    for (i = 0; i < ARRAY_SIZE(AceRights); i++)
     {
         if (AceRights[i].wstr == NULL)
             break;
@@ -5633,11 +5633,11 @@ static DWORD ComputeStringSidSize(LPCWSTR StringSid)
     {
         unsigned int i;
 
-        for (i = 0; i < sizeof(WellKnownSids)/sizeof(WellKnownSids[0]); i++)
+        for (i = 0; i < ARRAY_SIZE(WellKnownSids); i++)
             if (!strncmpW(WellKnownSids[i].wstr, StringSid, 2))
                 return GetSidLengthRequired(WellKnownSids[i].Sid.SubAuthorityCount);
 
-        for (i = 0; i < sizeof(WellKnownRids)/sizeof(WellKnownRids[0]); i++)
+        for (i = 0; i < ARRAY_SIZE(WellKnownRids); i++)
             if (!strncmpW(WellKnownRids[i].wstr, StringSid, 2))
             {
                 MAX_SID local;
@@ -5740,7 +5740,7 @@ static BOOL ParseStringSidToSid(LPCWSTR StringSid, PSID pSid, LPDWORD cBytes)
         unsigned int i;
         pisid->Revision = SDDL_REVISION;
 
-        for (i = 0; i < sizeof(WellKnownSids)/sizeof(WellKnownSids[0]); i++)
+        for (i = 0; i < ARRAY_SIZE(WellKnownSids); i++)
             if (!strncmpW(WellKnownSids[i].wstr, StringSid, 2))
             {
                 DWORD j;
@@ -5751,7 +5751,7 @@ static BOOL ParseStringSidToSid(LPCWSTR StringSid, PSID pSid, LPDWORD cBytes)
                 bret = TRUE;
             }
 
-        for (i = 0; i < sizeof(WellKnownRids)/sizeof(WellKnownRids[0]); i++)
+        for (i = 0; i < ARRAY_SIZE(WellKnownRids); i++)
             if (!strncmpW(WellKnownRids[i].wstr, StringSid, 2))
             {
                 ADVAPI_GetComputerSid(pisid);