diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1a5c8232..0886ad07 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -389,10 +389,13 @@ target_precompile_headers(libgui PRIVATE src/engine/pch.h)
 set(SCRIPT_HEADERS
     src/engine/script/enginetype.h
     src/engine/script/execution.h
+    src/engine/script/executioncontext.h
+    src/engine/script/executionstate.h
     src/engine/script/instrutil.h
     src/engine/script/ncsreader.h
     src/engine/script/program.h
     src/engine/script/routine.h
+    src/engine/script/routineprovider.h
     src/engine/script/services.h
     src/engine/script/scripts.h
     src/engine/script/types.h
diff --git a/src/engine/game/action/docommand.h b/src/engine/game/action/docommand.h
index ef8c51b5..e6b66634 100644
--- a/src/engine/game/action/docommand.h
+++ b/src/engine/game/action/docommand.h
@@ -17,12 +17,16 @@
 
 #pragma once
 
-#include "../../script/types.h"
-
 #include "action.h"
 
 namespace reone {
 
+namespace script {
+
+struct ExecutionContext;
+
+}
+
 namespace game {
 
 class CommandAction : public Action {
diff --git a/src/engine/game/actionexecutor.cpp b/src/engine/game/actionexecutor.cpp
index 81b61e30..28e756e3 100644
--- a/src/engine/game/actionexecutor.cpp
+++ b/src/engine/game/actionexecutor.cpp
@@ -21,6 +21,7 @@
 #include "../common/guardutil.h"
 #include "../scene/types.h"
 #include "../script/execution.h"
+#include "../script/executioncontext.h"
 
 #include "action/usefeat.h"
 #include "action/useskill.h"
diff --git a/src/engine/game/script/routines.cpp b/src/engine/game/script/routines.cpp
index 49e7d7f1..6ac603d7 100644
--- a/src/engine/game/script/routines.cpp
+++ b/src/engine/game/script/routines.cpp
@@ -17,6 +17,8 @@
 
 #include "routines.h"
 
+#include "../../script/executioncontext.h"
+
 #include "../enginetype/effect.h"
 #include "../enginetype/event.h"
 #include "../enginetype/location.h"
diff --git a/src/engine/game/script/routines.h b/src/engine/game/script/routines.h
index 62a7315a..f126db71 100644
--- a/src/engine/game/script/routines.h
+++ b/src/engine/game/script/routines.h
@@ -20,6 +20,7 @@
 #include "../../common/collectionutil.h"
 #include "../../resource/types.h"
 #include "../../script/routine.h"
+#include "../../script/routineprovider.h"
 #include "../../script/types.h"
 #include "../../script/variable.h"
 
diff --git a/src/engine/game/script/routines_common.cpp b/src/engine/game/script/routines_common.cpp
index b39987f1..d1787923 100644
--- a/src/engine/game/script/routines_common.cpp
+++ b/src/engine/game/script/routines_common.cpp
@@ -24,6 +24,7 @@
 #include "../../common/log.h"
 #include "../../common/random.h"
 #include "../../resource/strings.h"
+#include "../../script/executioncontext.h"
 
 #include "../game.h"
 
diff --git a/src/engine/game/script/routines_events.cpp b/src/engine/game/script/routines_events.cpp
index a25189e3..06b07f30 100644
--- a/src/engine/game/script/routines_events.cpp
+++ b/src/engine/game/script/routines_events.cpp
@@ -22,6 +22,7 @@
 #include "routines.h"
 
 #include "../../common/log.h"
+#include "../../script/executioncontext.h"
 
 #include "../enginetype/event.h"
 #include "../game.h"
diff --git a/src/engine/game/script/runner.cpp b/src/engine/game/script/runner.cpp
index 3e2cd951..6635ca44 100644
--- a/src/engine/game/script/runner.cpp
+++ b/src/engine/game/script/runner.cpp
@@ -18,6 +18,7 @@
 #include "runner.h"
 
 #include "../../script/execution.h"
+#include "../../script/executioncontext.h"
 
 #include "../game.h"
 
diff --git a/src/engine/script/execution.cpp b/src/engine/script/execution.cpp
index c3423e40..982e7d70 100644
--- a/src/engine/script/execution.cpp
+++ b/src/engine/script/execution.cpp
@@ -17,10 +17,15 @@
 
 #include "execution.h"
 
+#include "../common/guardutil.h"
 #include "../common/log.h"
 
+#include "executioncontext.h"
 #include "instrutil.h"
+#include "program.h"
 #include "routine.h"
+#include "routineprovider.h"
+#include "variable.h"
 
 using namespace std;
 using namespace std::placeholders;
@@ -31,7 +36,9 @@ namespace script {
 
 static constexpr int kStartInstructionOffset = 13;
 
-ScriptExecution::ScriptExecution(const shared_ptr<ScriptProgram> &program, unique_ptr<ExecutionContext> context) : _context(move(context)), _program(program) {
+ScriptExecution::ScriptExecution(shared_ptr<ScriptProgram> program, unique_ptr<ExecutionContext> context) : _context(move(context)), _program(program) {
+    ensureNotNull(program, "program");
+
     static unordered_map<ByteCode, function<void(ScriptExecution *, const Instruction &)>> handlers {
         { ByteCode::CopyDownSP, &ScriptExecution::executeCopyDownSP },
         { ByteCode::Reserve, &ScriptExecution::executeReserve },
diff --git a/src/engine/script/execution.h b/src/engine/script/execution.h
index 2679442d..29bb37f1 100644
--- a/src/engine/script/execution.h
+++ b/src/engine/script/execution.h
@@ -17,17 +17,22 @@
 
 #pragma once
 
-#include "program.h"
+#include "executionstate.h"
 #include "types.h"
-#include "variable.h"
 
 namespace reone {
 
 namespace script {
 
+struct ExecutionContext;
+struct Instruction;
+struct Variable;
+
+class ScriptProgram;
+
 class ScriptExecution : boost::noncopyable {
 public:
-    ScriptExecution(const std::shared_ptr<ScriptProgram> &program, std::unique_ptr<ExecutionContext> context);
+    ScriptExecution(std::shared_ptr<ScriptProgram> program, std::unique_ptr<ExecutionContext> context);
 
     int run();
 
diff --git a/src/engine/script/executioncontext.h b/src/engine/script/executioncontext.h
new file mode 100644
index 00000000..24f7c22a
--- /dev/null
+++ b/src/engine/script/executioncontext.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2020-2021 The reone project contributors
+ *
+ * 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 3 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "types.h"
+
+namespace reone {
+
+namespace script {
+
+struct ExecutionState;
+
+class IRoutineProvider;
+
+struct ExecutionContext {
+    IRoutineProvider *routines { nullptr };
+    std::shared_ptr<ExecutionState> savedState;
+    uint32_t callerId { kObjectInvalid };
+    uint32_t triggererId { kObjectInvalid };
+    int userDefinedEventNumber { -1 };
+    int scriptVar { -1 };
+};
+
+} // namespace script
+
+} // namespae reone
diff --git a/src/engine/script/executionstate.h b/src/engine/script/executionstate.h
new file mode 100644
index 00000000..ad14d459
--- /dev/null
+++ b/src/engine/script/executionstate.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2020-2021 The reone project contributors
+ *
+ * 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 3 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+namespace reone {
+
+namespace script {
+
+struct Variable;
+
+class ScriptProgram;
+
+struct ExecutionState {
+    std::shared_ptr<ScriptProgram> program;
+    std::vector<Variable> globals;
+    std::vector<Variable> locals;
+    uint32_t insOffset { 0 };
+};
+
+} // namespace script
+
+} // namespae reone
diff --git a/src/engine/script/ncsreader.cpp b/src/engine/script/ncsreader.cpp
index 597c1963..eac0fe13 100644
--- a/src/engine/script/ncsreader.cpp
+++ b/src/engine/script/ncsreader.cpp
@@ -19,6 +19,8 @@
 
 #include "../common/log.h"
 
+#include "program.h"
+
 using namespace std;
 
 namespace reone {
diff --git a/src/engine/script/ncsreader.h b/src/engine/script/ncsreader.h
index 2c7ec6bc..56ecce04 100644
--- a/src/engine/script/ncsreader.h
+++ b/src/engine/script/ncsreader.h
@@ -19,12 +19,12 @@
 
 #include "../resource/format/binreader.h"
 
-#include "program.h"
-
 namespace reone {
 
 namespace script {
 
+class ScriptProgram;
+
 /**
  * Parses compiled script program.
  *
diff --git a/src/engine/script/program.h b/src/engine/script/program.h
index 9cf1a2dc..233f8032 100644
--- a/src/engine/script/program.h
+++ b/src/engine/script/program.h
@@ -17,85 +17,12 @@
 
 #pragma once
 
+#include "types.h"
+
 namespace reone {
 
 namespace script {
 
-enum class ByteCode {
-    CopyDownSP = 0x01,
-    Reserve = 0x02,
-    CopyTopSP = 0x03,
-    PushConstant = 0x04,
-    CallRoutine = 0x05,
-    LogicalAnd = 0x06,
-    LogicalOr = 0x07,
-    InclusiveBitwiseOr = 0x08,
-    ExclusiveBitwiseOr = 0x09,
-    BitwiseAnd = 0x0a,
-    Equal = 0x0b,
-    NotEqual = 0x0c,
-    GreaterThanOrEqual = 0x0d,
-    GreaterThan = 0x0e,
-    LessThan = 0x0f,
-    LessThanOrEqual = 0x10,
-    ShiftLeft = 0x11,
-    ShiftRight = 0x12,
-    UnsignedShiftRight = 0x13,
-    Add = 0x14,
-    Subtract = 0x15,
-    Multiply = 0x16,
-    Divide = 0x17,
-    Mod = 0x18,
-    Negate = 0x19,
-    OnesComplement = 0x1a,
-    AdjustSP = 0x1b,
-    Jump = 0x1d,
-    JumpToSubroutine = 0x1e,
-    JumpIfZero = 0x1f,
-    Return = 0x20,
-    Destruct = 0x21,
-    LogicalNot = 0x22,
-    DecRelToSP = 0x23,
-    IncRelToSP = 0x24,
-    JumpIfNonZero = 0x25,
-    CopyDownBP = 0x26,
-    CopyTopBP = 0x27,
-    DecRelToBP = 0x28,
-    IncRelToBP = 0x29,
-    SaveBP = 0x2a,
-    RestoreBP = 0x2b,
-    StoreState = 0x2c,
-    Noop = 0x2d,
-    Invalid = 0xff
-};
-
-enum class InstructionType {
-    None = 0,
-    One = 0x01,
-    Int = 0x03,
-    Float = 0x04,
-    String = 0x05,
-    Object = 0x06,
-    Effect = 0x10,
-    Event = 0x11,
-    Location = 0x12,
-    Talent = 0x13,
-    IntInt = 0x20,
-    FloatFloat = 0x21,
-    ObjectObject = 0x22,
-    StringString = 0x23,
-    StructStruct = 0x24,
-    IntFloat = 0x25,
-    FloatInt = 0x26,
-    EffectEffect = 0x30,
-    EventEvent = 0x31,
-    LocationLocation = 0x32,
-    TalentTalent = 0x33,
-    VectorVector = 0x3a,
-    VectorFloat = 0x3b,
-    FloatVector = 0x3c
-};
-
 class NcsReader;
 
 struct Instruction {
diff --git a/src/engine/script/routine.cpp b/src/engine/script/routine.cpp
index 61b1090e..79d8dbb2 100644
--- a/src/engine/script/routine.cpp
+++ b/src/engine/script/routine.cpp
@@ -19,6 +19,8 @@
 
 #include "../common/log.h"
 
+#include "variable.h"
+
 using namespace std;
 
 namespace reone {
diff --git a/src/engine/script/routine.h b/src/engine/script/routine.h
index c5ad8899..501379ab 100644
--- a/src/engine/script/routine.h
+++ b/src/engine/script/routine.h
@@ -17,12 +17,15 @@
 
 #pragma once
 
-#include "variable.h"
+#include "types.h"
 
 namespace reone {
 
 namespace script {
 
+struct ExecutionContext;
+struct Variable;
+
 class Routine {
 public:
     Routine() = default;
diff --git a/src/engine/script/routineprovider.h b/src/engine/script/routineprovider.h
new file mode 100644
index 00000000..f46bfbe9
--- /dev/null
+++ b/src/engine/script/routineprovider.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2020-2021 The reone project contributors
+ *
+ * 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 3 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+namespace reone {
+
+namespace script {
+
+class Routine;
+
+class IRoutineProvider {
+public:
+    virtual ~IRoutineProvider() {
+    }
+
+    virtual const Routine &get(int index) = 0;
+};
+
+} // namespace script
+
+} // namespae reone
diff --git a/src/engine/script/types.h b/src/engine/script/types.h
index 1fedb112..e73ed8b0 100644
--- a/src/engine/script/types.h
+++ b/src/engine/script/types.h
@@ -24,33 +24,95 @@ namespace script {
 constexpr uint32_t kObjectSelf = 0;
 constexpr uint32_t kObjectInvalid = 1;
 
-struct Variable;
-
-class ScriptProgram;
-class Routine;
-
-struct ExecutionState {
-    std::shared_ptr<ScriptProgram> program;
-    std::vector<Variable> globals;
-    std::vector<Variable> locals;
-    uint32_t insOffset { 0 };
+enum class ByteCode {
+    CopyDownSP = 0x01,
+    Reserve = 0x02,
+    CopyTopSP = 0x03,
+    PushConstant = 0x04,
+    CallRoutine = 0x05,
+    LogicalAnd = 0x06,
+    LogicalOr = 0x07,
+    InclusiveBitwiseOr = 0x08,
+    ExclusiveBitwiseOr = 0x09,
+    BitwiseAnd = 0x0a,
+    Equal = 0x0b,
+    NotEqual = 0x0c,
+    GreaterThanOrEqual = 0x0d,
+    GreaterThan = 0x0e,
+    LessThan = 0x0f,
+    LessThanOrEqual = 0x10,
+    ShiftLeft = 0x11,
+    ShiftRight = 0x12,
+    UnsignedShiftRight = 0x13,
+    Add = 0x14,
+    Subtract = 0x15,
+    Multiply = 0x16,
+    Divide = 0x17,
+    Mod = 0x18,
+    Negate = 0x19,
+    OnesComplement = 0x1a,
+    AdjustSP = 0x1b,
+    Jump = 0x1d,
+    JumpToSubroutine = 0x1e,
+    JumpIfZero = 0x1f,
+    Return = 0x20,
+    Destruct = 0x21,
+    LogicalNot = 0x22,
+    DecRelToSP = 0x23,
+    IncRelToSP = 0x24,
+    JumpIfNonZero = 0x25,
+    CopyDownBP = 0x26,
+    CopyTopBP = 0x27,
+    DecRelToBP = 0x28,
+    IncRelToBP = 0x29,
+    SaveBP = 0x2a,
+    RestoreBP = 0x2b,
+    StoreState = 0x2c,
+    Noop = 0x2d,
+    Invalid = 0xff
 };
 
-class IRoutineProvider {
-public:
-    virtual ~IRoutineProvider() {
-    }
-
-    virtual const Routine &get(int index) = 0;
+enum class InstructionType {
+    None = 0,
+    One = 0x01,
+    Int = 0x03,
+    Float = 0x04,
+    String = 0x05,
+    Object = 0x06,
+    Effect = 0x10,
+    Event = 0x11,
+    Location = 0x12,
+    Talent = 0x13,
+    IntInt = 0x20,
+    FloatFloat = 0x21,
+    ObjectObject = 0x22,
+    StringString = 0x23,
+    StructStruct = 0x24,
+    IntFloat = 0x25,
+    FloatInt = 0x26,
+    EffectEffect = 0x30,
+    EventEvent = 0x31,
+    LocationLocation = 0x32,
+    TalentTalent = 0x33,
+    VectorVector = 0x3a,
+    VectorFloat = 0x3b,
+    FloatVector = 0x3c
 };
 
-struct ExecutionContext {
-    IRoutineProvider *routines { nullptr };
-    std::shared_ptr<ExecutionState> savedState;
-    uint32_t callerId { kObjectInvalid };
-    uint32_t triggererId { kObjectInvalid };
-    int userDefinedEventNumber { -1 };
-    int scriptVar { -1 };
+enum class VariableType {
+    Void,
+    Int,
+    Float,
+    String,
+    Vector,
+    Object,
+    Effect,
+    Event,
+    Location,
+    Talent,
+    Action,
+
+    NotImplemented // used to return default values from placeholder routines
 };
 
 } // namespace script
diff --git a/src/engine/script/variable.h b/src/engine/script/variable.h
index e79a02a8..0b11c2f9 100644
--- a/src/engine/script/variable.h
+++ b/src/engine/script/variable.h
@@ -23,21 +23,7 @@ namespace reone {
 
 namespace script {
 
-enum class VariableType {
-    Void,
-    Int,
-    Float,
-    String,
-    Vector,
-    Object,
-    Effect,
-    Event,
-    Location,
-    Talent,
-    Action,
-
-    NotImplemented // used to return default values from placeholder routines
-};
+struct ExecutionContext;
 
 class EngineType;
 class ScriptObject;
diff --git a/src/tests/script/execution.cpp b/src/tests/script/execution.cpp
index 0ae905b2..b0296669 100644
--- a/src/tests/script/execution.cpp
+++ b/src/tests/script/execution.cpp
@@ -22,6 +22,9 @@
 #include <boost/test/unit_test.hpp>
 
 #include "../../engine/script/execution.h"
+#include "../../engine/script/executioncontext.h"
+#include "../../engine/script/program.h"
+#include "../../engine/script/variable.h"
 
 using namespace std;