diff --git a/src/aria2.cpp b/src/aria2.cpp
index 544057006..0195cccd0 100644
--- a/src/aria2.cpp
+++ b/src/aria2.cpp
@@ -61,7 +61,6 @@ Aria2::Aria2():
   callCmd.push_back("--max-concurrent-downloads=42");
   callCmd.push_back("--rpc-max-request-size=6M");
   callCmd.push_back("--file-allocation=none");
-  callCmd.push_back(NULL);
   mp_aria = Subprocess::run(callCmd);
   mp_curl = curl_easy_init();
   curl_easy_setopt(mp_curl, CURLOPT_URL, "http://localhost/rpc");
diff --git a/src/subprocess.cpp b/src/subprocess.cpp
index 6c958c489..b69cbc78e 100644
--- a/src/subprocess.cpp
+++ b/src/subprocess.cpp
@@ -8,7 +8,7 @@
 # include "subprocess_unix.h"
 #endif
 
-Subprocess::Subprocess(std::unique_ptr<SubprocessImpl> impl, const commandLine_t& commandLine) :
+Subprocess::Subprocess(std::unique_ptr<SubprocessImpl> impl, commandLine_t& commandLine) :
   mp_impl(std::move(impl))
 {
   mp_impl->run(commandLine);
@@ -19,7 +19,7 @@ Subprocess::~Subprocess()
   mp_impl->kill();
 }
 
-std::unique_ptr<Subprocess> Subprocess::run(const commandLine_t& commandLine)
+std::unique_ptr<Subprocess> Subprocess::run(commandLine_t& commandLine)
 {
 #ifdef _WIN32
   auto impl = std::unique_ptr<SubprocessImpl>(new WinImpl);
diff --git a/src/subprocess.h b/src/subprocess.h
index 9ed75eb21..2fa7dccad 100644
--- a/src/subprocess.h
+++ b/src/subprocess.h
@@ -11,7 +11,7 @@ typedef std::vector<const char *> commandLine_t;
 class SubprocessImpl
 {
   public:
-    virtual void run(const commandLine_t& commandLine) = 0;
+    virtual void run(commandLine_t& commandLine) = 0;
     virtual bool kill() = 0;
     virtual bool isRunning() = 0;
     virtual ~SubprocessImpl() = default;
@@ -22,10 +22,10 @@ class Subprocess
   private:
     // Impl depends of the system (window, unix, ...)
     std::unique_ptr<SubprocessImpl> mp_impl;
-    Subprocess(std::unique_ptr<SubprocessImpl> impl, const commandLine_t& commandLine);
+    Subprocess(std::unique_ptr<SubprocessImpl> impl, commandLine_t& commandLine);
 
   public:
-    static std::unique_ptr<Subprocess> run(const commandLine_t& commandLine);
+    static std::unique_ptr<Subprocess> run(commandLine_t& commandLine);
     ~Subprocess();
 
     bool isRunning();
diff --git a/src/subprocess_unix.cpp b/src/subprocess_unix.cpp
index 08586f952..01921fde1 100644
--- a/src/subprocess_unix.cpp
+++ b/src/subprocess_unix.cpp
@@ -55,7 +55,7 @@ void* UnixImpl::waitForPID(void* _self)
   return self;
 }
 
-void UnixImpl::run(const commandLine_t& commandLine)
+void UnixImpl::run(commandLine_t& commandLine)
 {
   const char* binary = commandLine[0];
   int pid = fork();
@@ -64,6 +64,7 @@ void UnixImpl::run(const commandLine_t& commandLine)
       std::cerr << "cannot fork" << std::endl;
       break;
     case 0:
+      commandLine.push_back(NULL);
       if (execvp(binary, const_cast<char* const*>(commandLine.data()))) {
         perror("Cannot launch\n");
         exit(-1);
diff --git a/src/subprocess_unix.h b/src/subprocess_unix.h
index 750658943..22a03b525 100644
--- a/src/subprocess_unix.h
+++ b/src/subprocess_unix.h
@@ -18,7 +18,7 @@ class UnixImpl : public SubprocessImpl
     UnixImpl();
     virtual ~UnixImpl();
 
-    void run(const commandLine_t& commandLine);
+    void run(commandLine_t& commandLine);
     bool kill();
     bool isRunning();
 
diff --git a/src/subprocess_windows.cpp b/src/subprocess_windows.cpp
index 54c36824d..c49d4d841 100644
--- a/src/subprocess_windows.cpp
+++ b/src/subprocess_windows.cpp
@@ -50,7 +50,7 @@ std::unique_ptr<wchar_t[]> toWideChar(const std::string& value)
 }
 
 
-void WinImpl::run(const commandLine_t& commandLine)
+void WinImpl::run(commandLine_t& commandLine)
 {
   STARTUPINFOW startInfo = {0};
   PROCESS_INFORMATION procInfo;
diff --git a/src/subprocess_windows.h b/src/subprocess_windows.h
index 40b5a0904..36e1b0127 100644
--- a/src/subprocess_windows.h
+++ b/src/subprocess_windows.h
@@ -18,7 +18,7 @@ class WinImpl : public SubprocessImpl
     WinImpl();
     virtual ~WinImpl();
 
-    void run(const commandLine_t& commandLine);
+    void run(commandLine_t& commandLine);
     bool kill();
     bool isRunning();