--- a/mfbt/Compiler.h
+++ b/mfbt/Compiler.h
@@ -21,18 +21,18 @@
     * for gcc 4.7.1 or later, check `#if MOZ_GCC_VERSION_AT_LEAST(4, 7, 1)`.
     */
 #  define MOZ_GCC_VERSION_AT_LEAST(major, minor, patchlevel)          \
      ((__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) \
       >= ((major) * 10000 + (minor) * 100 + (patchlevel)))
 #  define MOZ_GCC_VERSION_AT_MOST(major, minor, patchlevel)           \
      ((__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) \
       <= ((major) * 10000 + (minor) * 100 + (patchlevel)))
-#  if !MOZ_GCC_VERSION_AT_LEAST(4, 9, 0)
-#    error "mfbt (and Gecko) require at least gcc 4.9 to build."
+#  if !MOZ_GCC_VERSION_AT_LEAST(6, 1, 0)
+#    error "mfbt (and Gecko) require at least gcc 6.1 to build."
 #  endif
 
 #elif defined(_MSC_VER)
 
 #  undef MOZ_IS_MSVC
 #  define MOZ_IS_MSVC 1
 
 #endif