diff --git a/configure b/configure
index a314719..a59cda1 100755
--- a/configure
+++ b/configure
@@ -40433,7 +40433,7 @@ char BZ2_bzlibVersion ();
 
 #endif
 int
-main ()
+main (void)
 {
 return BZ2_bzlibVersion ();
   ;
@@ -40494,9 +40494,11 @@ else
 /* end confdefs.h.  */
 
 #ifdef HAVE_BZLIB_H
+#include <stdlib.h> // for exit
+#include <string.h> // for strcmp
 #include <bzlib.h>
 #endif
-int main() {
+int main(void) {
     char *ver = BZ2_bzlibVersion();
     exit(strcmp(ver, "1.0.6") < 0);
 }
@@ -41072,6 +41074,7 @@ else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
+#include <stdlib.h>
 #include <string.h>
 #include <curl/curl.h>
 int main()