diff --git a/configure.ac b/configure.ac
index 3ad454b2..7fa14d4a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -407,8 +407,7 @@ dnl Checks for functions and headers
 
 AS_IF([test "x$EMSCRIPTEN" = "x"],[
   AC_CHECK_FUNCS([arc4random arc4random_buf])
-  AC_CHECK_FUNCS([mlock madvise mprotect explicit_bzero])
-  AC_FUNC_MMAP
+  AC_CHECK_FUNCS([mmap mlock madvise mprotect explicit_bzero])
 ])
 AC_CHECK_FUNCS([posix_memalign])