diff --git a/configure b/configure
index d8ec050..c2955f8 100755
--- a/configure
+++ b/configure
@@ -2255,7 +2255,7 @@ cat > $TMPC <<EOF
 #include <sys/types.h>
 #include <sys/uio.h>
 #include <unistd.h>
-int main(void) { return preadv == preadv; }
+int main(void) { return preadv(0, (void *)0, 0, 0); }
 EOF
 preadv=no
 if compile_prog "" "" ; then
@@ -2551,7 +2551,7 @@ int main(void)
      * warning but not an error, and will proceed to fail the
      * qemu compile where we compile with -Werror.)
      */
-    return epoll_create1 == epoll_create1;
+    return (int)(uintptr_t)&epoll_create1;
 }
 EOF
 if compile_prog "" "" ; then
@@ -2944,7 +2944,7 @@ has_environ=no
 cat > $TMPC << EOF
 #include <unistd.h>
 int main(void) {
-    environ = environ;
+    environ = (void *)0;
     return 0;
 }
 EOF