diff --git a/core.c b/core.c
index 42ef405..1b7ee39 100644
--- a/core.c
+++ b/core.c
@@ -57,6 +57,7 @@
 		ROUTE_ENDPOINT,
 		ROUTE_BRIDGE,
 	}			route_policy;
+	size_t max_message_size;
 };
 
 #ifndef BUILD_ASSERT
@@ -68,6 +69,12 @@
 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
 #endif
 
+/* 64kb should be sufficient for a single message. Applications
+ * requiring higher sizes can override by setting max_message_size.*/
+#ifndef MCTP_MAX_MESSAGE_SIZE
+#define MCTP_MAX_MESSAGE_SIZE 65536
+#endif
+
 static int mctp_message_tx_on_bus(struct mctp_bus *bus, mctp_eid_t src,
 				  mctp_eid_t dest, void *msg, size_t msg_len);
 
@@ -195,7 +202,7 @@
 }
 
 static int mctp_msg_ctx_add_pkt(struct mctp_msg_ctx *ctx,
-		struct mctp_pktbuf *pkt)
+		struct mctp_pktbuf *pkt, size_t max_size)
 {
 	size_t len;
 
@@ -212,6 +219,11 @@
 			new_alloc_size = ctx->buf_alloc_size * 2;
 		}
 
+		/* Don't allow heap to grow beyond a limit */
+		if (new_alloc_size > max_size)
+			return -1;
+
+
 		lbuf = __mctp_realloc(ctx->buf, new_alloc_size);
 		if (lbuf) {
 			ctx->buf = lbuf;
@@ -235,10 +247,16 @@
 
 	mctp = __mctp_alloc(sizeof(*mctp));
 	memset(mctp, 0, sizeof(*mctp));
+	mctp->max_message_size = MCTP_MAX_MESSAGE_SIZE;
 
 	return mctp;
 }
 
+void mctp_set_max_message_size(struct mctp *mctp, size_t message_size)
+{
+	mctp->max_message_size = message_size;
+}
+
 void mctp_destroy(struct mctp *mctp)
 {
 	size_t i;
@@ -470,7 +488,7 @@
 					hdr->src, hdr->dest, tag);
 		}
 
-		rc = mctp_msg_ctx_add_pkt(ctx, pkt);
+		rc = mctp_msg_ctx_add_pkt(ctx, pkt, mctp->max_message_size);
 		if (rc) {
 			mctp_msg_ctx_drop(ctx);
 		} else {
@@ -494,7 +512,7 @@
 			goto out;
 		}
 
-		rc = mctp_msg_ctx_add_pkt(ctx, pkt);
+		rc = mctp_msg_ctx_add_pkt(ctx, pkt, mctp->max_message_size);
 		if (!rc)
 			mctp_rx(mctp, bus, ctx->src, ctx->dest,
 					ctx->buf, ctx->buf_size);
@@ -517,7 +535,7 @@
 			goto out;
 		}
 
-		rc = mctp_msg_ctx_add_pkt(ctx, pkt);
+		rc = mctp_msg_ctx_add_pkt(ctx, pkt, mctp->max_message_size);
 		if (rc) {
 			mctp_msg_ctx_drop(ctx);
 			goto out;
diff --git a/libmctp.h b/libmctp.h
index a8beb72..00bce29 100644
--- a/libmctp.h
+++ b/libmctp.h
@@ -65,6 +65,7 @@
 struct mctp_bus;
 
 struct mctp *mctp_init(void);
+void mctp_set_max_message_size(struct mctp *mctp, size_t message_size);
 void mctp_destroy(struct mctp *mctp);
 
 /* Register a binding to the MCTP core, and creates a bus (populating