diff --git a/Modules.cpp b/Modules.cpp
index eb3bdc50..7b1729d2 100644
--- a/Modules.cpp
+++ b/Modules.cpp
@@ -498,6 +498,7 @@ CModule::EModRet CGlobalModule::OnConfigLine(const CString& sName, const CString
 CModule::EModRet CGlobalModule::OnWriteConfig(CFile& Config) { return CONTINUE; }
 void CGlobalModule::OnWriteUserConfig(CFile& Config, CUser& User) {}
 void CGlobalModule::OnWriteChanConfig(CFile& Config, CChan& Chan) {}
+CModule::EModRet CGlobalModule::OnAddUser(CUser& User, CString& sErrorRet) { return CONTINUE; }
 CModule::EModRet CGlobalModule::OnDeleteUser(CUser& User) { return CONTINUE; }
 void CGlobalModule::OnClientConnect(CClient* pClient, const CString& sHost, unsigned short uPort) {}
 CModule::EModRet CGlobalModule::OnLoginAttempt(CSmartPtr<CAuthBase> Auth) { return CONTINUE; }
@@ -612,6 +613,10 @@ void CGlobalModules::OnWriteChanConfig(CFile& Config, CChan& Chan) {
 	GLOBALMODCALL(OnWriteChanConfig(Config, Chan));
 }
 
+bool CGlobalModules::OnAddUser(CUser& User, CString& sErrorRet) {
+	GLOBALMODHALTCHK(OnAddUser(User, sErrorRet));
+}
+
 bool CGlobalModules::OnDeleteUser(CUser& User) {
 	GLOBALMODHALTCHK(OnDeleteUser(User));
 }
diff --git a/Modules.h b/Modules.h
index ddf3ad46..9f63bced 100644
--- a/Modules.h
+++ b/Modules.h
@@ -888,6 +888,13 @@ public:
 	 *  @param Chan The channel which is being written.
 	 */
 	virtual void OnWriteChanConfig(CFile& Config, CChan& Chan);
+	/** This module hook is called when a user is being added.
+	 * @param User The user which will be added.
+	 * @param sErrorRet A message that may be displayed to the user if
+	 * 	the module stops adding the user.
+	 * @return See CModule::EModRet.
+	 */
+	virtual EModRet OnAddUser(CUser& User, CString& sErrorRet);
 	/** This module hook is called when a user is deleted.
 	 *  @param User The user which will be deleted.
 	 *  @return See CModule::EModRet.
@@ -933,6 +940,7 @@ public:
 	bool OnWriteConfig(CFile& Config);
 	void OnWriteUserConfig(CFile& Config, CUser& User);
 	void OnWriteChanConfig(CFile& Config, CChan& Chan);
+	bool OnAddUser(CUser& User, CString& sErrorRet);
 	bool OnDeleteUser(CUser& User);
 	void OnClientConnect(CClient* pClient, const CString& sHost, unsigned short uPort);
 	bool OnLoginAttempt(CSmartPtr<CAuthBase> Auth);
diff --git a/znc.cpp b/znc.cpp
index dbf997cc..9ca8cec2 100644
--- a/znc.cpp
+++ b/znc.cpp
@@ -1803,6 +1803,11 @@ bool CZNC::AddUser(CUser* pUser, CString& sErrorRet) {
 				<< sErrorRet << "]");
 		return false;
 	}
+	if (!GetModules().OnAddUser(*pUser, sErrorRet)) {
+		DEBUG("AddUser [" << pUser->GetUserName() << "] aborted by a module ["
+			<< sErrorRet << "]");
+		return false;
+	}
 	m_msUsers[pUser->GetUserName()] = pUser;
 	return true;
 }