diff --git a/js/src/util/NativeStack.cpp b/js/src/util/NativeStack.cpp
--- a/js/src/util/NativeStack.cpp
+++ b/js/src/util/NativeStack.cpp
@@ -25,7 +25,7 @@
 #    include <sys/syscall.h>
 #    include <sys/types.h>
 #    include <unistd.h>
-static pid_t gettid() { return syscall(__NR_gettid); }
+#    define gettid() static_cast<pid_t>(syscall(__NR_gettid))
 #  endif
 #else
 #  error "Unsupported platform"
diff --git a/tools/profiler/core/platform.h b/tools/profiler/core/platform.h
--- a/tools/profiler/core/platform.h
+++ b/tools/profiler/core/platform.h
@@ -39,16 +39,16 @@
 #include <functional>
 #include <stdint.h>
 
-// We need a definition of gettid(), but glibc doesn't provide a
+// We need a definition of gettid(), but old glibc versions don't provide a
 // wrapper for it.
 #if defined(__GLIBC__)
 #  include <unistd.h>
 #  include <sys/syscall.h>
-static inline pid_t gettid() { return (pid_t)syscall(SYS_gettid); }
+#  define gettid() static_cast<pid_t>(syscall(SYS_gettid))
 #elif defined(GP_OS_darwin)
 #  include <unistd.h>
 #  include <sys/syscall.h>
-static inline pid_t gettid() { return (pid_t)syscall(SYS_thread_selfid); }
+#  define gettid() static_cast<pid_t>(syscall(SYS_thread_selfid))
 #elif defined(GP_OS_android)
 #  include <unistd.h>
 #elif defined(GP_OS_windows)