diff --git a/configure.in b/configure.in
index d3ae179..9232ac1 100644
--- a/configure.in
+++ b/configure.in
@@ -142,6 +142,7 @@ AC_MSG_CHECKING(if underscores are needed for symbols)
 AC_TRY_RUN(
 #include <dlfcn.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 int underscoreprobe(void) { return (31415); }
 
@@ -166,6 +167,7 @@ AC_MSG_CHECKING(if we can access libc without dlopen)
 AC_TRY_RUN(
 #include <dlfcn.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 int
 main(int argc, char **argv)