Can realloc(p,0) return NULL when p is non-NULL and memory aplenty?

When running the following code under MinGW, I get
realloc(p,0) returned NULL
Is that a non-conformance?

TIA,
  Francois Grieu

#include <stdio.h>
#include <stdlib.h>

int main(void)
	{
	void *p;
	p = malloc(0);
	if (p==NULL)
		puts("malloc(0) returned NULL");
	else
		{
		p = realloc(p,0);
		if (p==NULL)
			puts("realloc(p,0) returned NULL");
		else
			puts("realloc(p,0) did not return NULL");
		}
	return 0;
	}