--- a/modules/libfabric/src/mem.c
+++ b/modules/libfabric/src/mem.c
@@ -104,6 +104,23 @@ void ofi_mem_fini(void)
 	free(page_sizes);
 }
 
+#if defined(__APPLE__) && !defined(_SC_PHYS_PAGES)
+
+#include <sys/sysctl.h>
+
+size_t ofi_get_mem_size(void)
+{
+	uint64_t mem_size;
+	size_t len;
+
+	len = sizeof(mem_size);
+	sysctlbyname("hw.memsize", &mem_size, &len, NULL, 0);
+
+	return (size_t) mem_size;
+}
+
+#else
+
 size_t ofi_get_mem_size(void)
 {
 	long page_cnt, page_size;
@@ -122,6 +139,7 @@ size_t ofi_get_mem_size(void)
 	return mem_size;
 }
 
+#endif
 
 uint64_t OFI_RMA_PMEM;
 void (*ofi_pmem_commit)(const void *addr, size_t len);