diff --git a/thirdparty/cotire.cmake b/thirdparty/cotire.cmake
index 075ec79..18b55d8 100644
--- a/thirdparty/cotire.cmake
+++ b/thirdparty/cotire.cmake
@@ -1136,6 +1136,11 @@ function (cotire_parse_includes _language _scanOutput _ignoredIncludeDirs _honor
 	string (REPLACE ";" "\\;" _scanOutput "${_scanOutput}")
 	# then separate lines
 	string (REGEX REPLACE "\n" ";" _scanOutput "${_scanOutput}")
+	if ("${_language}" STREQUAL "CXX")
+	    # Fix clang9's libc++ errno
+	    message (STATUS "replacing <stdlib.h> with <cstdlib>")
+	    string (REGEX REPLACE "include_next" "include" _scanOutput "${_scanOutput}")
+	endif()
 	list (LENGTH _scanOutput _len)
 	# remove duplicate lines to speed up parsing
 	list (REMOVE_DUPLICATES _scanOutput)