diff --git a/Common.vcxproj b/Common.vcxproj
index d5daff0..91f2842 100644
--- a/Common.vcxproj
+++ b/Common.vcxproj
@@ -182,6 +182,7 @@
     <ClInclude Include="IFilter.h" />
     <ClInclude Include="IFilterFactory.h" />
     <ClInclude Include="libHybridConv-0.1.1\libHybridConv_eapo.h" />
+    <ClInclude Include="parser\LogicalOperators.h" />
     <ClInclude Include="parser\RegexFunctions.h" />
     <ClInclude Include="parser\RegistryFunctions.h" />
     <ClInclude Include="parser\StringOperators.h" />
@@ -230,6 +231,7 @@
     <ClCompile Include="helpers\VSTPluginLibrary.cpp" />
     <ClCompile Include="IFilter.cpp" />
     <ClCompile Include="libHybridConv-0.1.1\libHybridConv_eapo.cpp" />
+    <ClCompile Include="parser\LogicalOperators.cpp" />
     <ClCompile Include="parser\RegexFunctions.cpp" />
     <ClCompile Include="parser\RegistryFunctions.cpp" />
     <ClCompile Include="parser\StringOperators.cpp" />
diff --git a/Common.vcxproj.filters b/Common.vcxproj.filters
index 690105f..38f7b2b 100644
--- a/Common.vcxproj.filters
+++ b/Common.vcxproj.filters
@@ -141,6 +141,9 @@
     <ClInclude Include="filters\loudnessCorrection\LoudnessCorrectionFilter.h">
       <Filter>filters\loudnessCorrection</Filter>
     </ClInclude>
+    <ClInclude Include="parser\LogicalOperators.h">
+      <Filter>parser</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="stdafx.cpp" />
@@ -267,6 +270,9 @@
     <ClCompile Include="filters\loudnessCorrection\LoudnessCorrectionFilter.cpp">
       <Filter>filters\loudnessCorrection</Filter>
     </ClCompile>
+    <ClCompile Include="parser\LogicalOperators.cpp">
+      <Filter>parser</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <Filter Include="filters">
diff --git a/Editor/Editor.pro b/Editor/Editor.pro
index 8330019..514cd8c 100644
--- a/Editor/Editor.pro
+++ b/Editor/Editor.pro
@@ -21,6 +21,7 @@ SOURCES += main.cpp\
 	../helpers/LogHelper.cpp \
 	../helpers/StringHelper.cpp \
 	../helpers/RegistryHelper.cpp \
+	../parser/LogicalOperators.cpp \
 	IFilterGUIFactory.cpp \
 	IFilterGUI.cpp \
 	guis/PreampFilterGUI.cpp \
@@ -139,6 +140,7 @@ HEADERS  += \
 	../helpers/LogHelper.h \
 	../helpers/StringHelper.h \
 	../helpers/RegistryHelper.h \
+	../parser/LogicalOperators.h \
 	IFilterGUIFactory.h \
 	stable.h \
 	IFilterGUI.h \
diff --git a/filters/ExpressionFilterFactory.cpp b/filters/ExpressionFilterFactory.cpp
index 2725282..815e24a 100644
--- a/filters/ExpressionFilterFactory.cpp
+++ b/filters/ExpressionFilterFactory.cpp
@@ -25,6 +25,7 @@
 #include "parser/RegexFunctions.h"
 #include "parser/RegistryFunctions.h"
 #include "parser/StringOperators.h"
+#include "parser/LogicalOperators.h"
 #include "FilterEngine.h"
 #include "ExpressionFilterFactory.h"
 
@@ -45,6 +46,7 @@ void ExpressionFilterFactory::initialize(FilterEngine* engine)
 
 	parser->RemoveOprt(L"+");
 	parser->DefineOprt(new AddOperator());
+	parser->DefineInfixOprt(new NotOperator());
 }
 
 vector<IFilter*> ExpressionFilterFactory::createFilter(const wstring& configPath, wstring& command, wstring& parameters)
diff --git a/parser/LogicalOperators.cpp b/parser/LogicalOperators.cpp
new file mode 100644
index 0000000..e321e3d
--- /dev/null
+++ b/parser/LogicalOperators.cpp
@@ -0,0 +1,44 @@
+/*
+    This file is part of Equalizer APO, a system-wide equalizer.
+    Copyright (C) 2019  Jonas Thedering
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "stdafx.h"
+#include "LogicalOperators.h"
+
+using namespace std;
+using namespace mup;
+
+NotOperator::NotOperator()
+	: IOprtInfix(L"not", prINFIX)
+{}
+
+void NotOperator::Eval(ptr_val_type& ret, const ptr_val_type* arg, int argc)
+{
+	assert(argc == 1);
+	*ret = !arg[0]->GetBool();
+}
+
+const char_type* NotOperator::GetDesc() const
+{
+	return L"logical not";
+}
+
+IToken* NotOperator::Clone() const
+{
+	return new NotOperator(*this);
+}
diff --git a/parser/LogicalOperators.h b/parser/LogicalOperators.h
new file mode 100644
index 0000000..bd025b2
--- /dev/null
+++ b/parser/LogicalOperators.h
@@ -0,0 +1,32 @@
+/*
+    This file is part of Equalizer APO, a system-wide equalizer.
+    Copyright (C) 2019  Jonas Thedering
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+
+#include <mpParser.h>
+#include <mpOprtNonCmplx.h>
+
+class NotOperator : public mup::IOprtInfix
+{
+public:
+	NotOperator();
+	void Eval(mup::ptr_val_type& ret, const mup::ptr_val_type* arg, int argc) override;
+	const mup::char_type* GetDesc() const;
+	mup::IToken* Clone() const override;
+};