diff -ur a/unix/configure b/unix/configure
--- a/unix/configure	2008-06-19 21:32:20.000000000 -0600
+++ b/unix/configure	2023-07-11 10:02:57.809867694 -0600
@@ -519,7 +519,10 @@
 
 
 echo Check for memset
-echo "int main(){ char k; memset(&k,0,0); return 0; }" > conftest.c
+cat > conftest.c << _EOF_
+#include <string.h>
+int main(){ char k; memset(&k,0,0); return 0; }
+_EOF_
 $CC -o conftest conftest.c >/dev/null 2>/dev/null
 [ $? -ne 0 ] && CFLAGS="${CFLAGS} -DZMEM"