https://github.com/boostorg/process/issues/536
--- a/libs/process/src/ext/cmd.cpp
+++ b/libs/process/src/ext/cmd.cpp
@@ -219,7 +219,7 @@ shell cmd(boost::process::v2::pid_type pid, error_code & ec)
     procargs.resize(4096);
     int f = ::open(("/proc/" + std::to_string(pid) + "/cmdline").c_str(), O_RDONLY);
 
-    while (procargs.back() != EOF)
+    while (procargs.back() != (char) EOF)
     {
         auto r = ::read(f, &*(procargs.end() - 4096), 4096);
         if (r < 0)
@@ -237,7 +237,7 @@ shell cmd(boost::process::v2::pid_type pid, error_code & ec)
     }
     ::close(f);
 
-    if (procargs.back() == EOF)
+    if (procargs.back() == (char) EOF)
         procargs.pop_back();
 
     auto argc = std::count(procargs.begin(), procargs.end(), '\0');
--- a/libs/process/src/ext/env.cpp
+++ b/libs/process/src/ext/env.cpp
@@ -127,7 +127,7 @@ native_env_iterator next(native_env_iterator nh)
 }
 native_env_iterator find_end(native_env_iterator nh)
 {
-    while (*nh != EOF)
+    while (*nh != (char) EOF)
         nh ++;
     return nh ;
 }
@@ -318,7 +318,7 @@ env_view env(boost::process::v2::pid_type pid, error_code & ec)
 
     int f = ::open(("/proc/" + std::to_string(pid) + "/environ").c_str(), O_RDONLY);
 
-    while (!procargs || procargs.get()[size - 1] != EOF)
+    while (!procargs || procargs.get()[size - 1] != (char) EOF)
     {
         std::unique_ptr<char, detail::ext::native_env_handle_deleter> buf{new char[size + 4096]};
         if (size > 0)