diff --git a/sys/dev/e1000/if_em.c b/sys/dev/e1000/if_em.c
--- a/sys/dev/e1000/if_em.c
+++ b/sys/dev/e1000/if_em.c
@@ -31,7 +31,7 @@
 #include <sys/sbuf.h>
 #include <machine/_inttypes.h>
 
-#define em_mac_min e1000_82547
+#define em_mac_min e1000_82571
 #define igb_mac_min e1000_82575
 
 /*********************************************************************
@@ -2469,13 +2469,22 @@
 	 * the remainder is used for the transmit buffer.
 	 */
 	switch (hw->mac.type) {
-	/* Total Packet Buffer on these is 48K */
+	/* 82547: Total Packet Buffer is 40K */
+	case e1000_82547:
+	case e1000_82547_rev_2:
+		if (hw->mac.max_frame_size > 8192)
+			pba = E1000_PBA_22K; /* 22K for Rx, 18K for Tx */
+		else
+			pba = E1000_PBA_30K; /* 30K for Rx, 10K for Tx */
+		break;
+	/* 82571/82572/80003es2lan: Total Packet Buffer is 48K */
 	case e1000_82571:
 	case e1000_82572:
 	case e1000_80003es2lan:
 			pba = E1000_PBA_32K; /* 32K for Rx, 16K for Tx */
 		break;
-	case e1000_82573: /* 82573: Total Packet Buffer is 32K */
+	/* 82573: Total Packet Buffer is 32K */
+	case e1000_82573:
 			pba = E1000_PBA_12K; /* 12K for Rx, 20K for Tx */
 		break;
 	case e1000_82574:
@@ -2520,6 +2529,7 @@
 		pba = E1000_PBA_34K;
 		break;
 	default:
+		/* Remaining devices assumed to have a Packet Buffer of 64K. */
 		if (hw->mac.max_frame_size > 8192)
 			pba = E1000_PBA_40K; /* 40K for Rx, 24K for Tx */
 		else