diff --git a/conf/options/charon.opt b/conf/options/charon.opt
index 369a11df58..dc9eb067c0 100644
--- a/conf/options/charon.opt
+++ b/conf/options/charon.opt
@@ -154,8 +154,16 @@ charon.fragment_size = 1280
 	Maximum size (complete IP datagram size in bytes) of a sent IKE fragment
 	when using proprietary IKEv1 or standardized IKEv2 fragmentation, defaults
 	to 1280 (use 0 for address family specific default values, which uses a
-	lower value for IPv4).  If specified this limit is used for both IPv4 and
-	IPv6.
+	lower value for IPv4).  Unless overridden, this limit is used for both IPv4
+	and IPv6 if specified.
+
+charon.fragment_size_v4 = charon.fragment_size
+	Maximum size (complete IPv4 datagram size in bytes) of a sent IKE fragment
+	when using proprietary IKEv1 or standardized IKEv2 fragmentation.
+
+charon.fragment_size_v6 = charon.fragment_size
+	Maximum size (complete IPv6 datagram size in bytes) of a sent IKE fragment
+	when using proprietary IKEv1 or standardized IKEv2 fragmentation.
 
 charon.group
 	Name of the group the daemon changes to after startup.
diff --git a/src/libcharon/encoding/message.c b/src/libcharon/encoding/message.c
index 1686baeae1..ba0c174334 100644
--- a/src/libcharon/encoding/message.c
+++ b/src/libcharon/encoding/message.c
@@ -1999,10 +1999,6 @@ METHOD(message_t, fragment, status_t,
 
 	src = this->packet->get_source(this->packet);
 	dst = this->packet->get_destination(this->packet);
-	if (!frag_len)
-	{
-		frag_len = (src->get_family(src) == AF_INET) ? 576 : 1280;
-	}
 	/* frag_len is the complete IP datagram length, account for overhead (we
 	 * assume no IP options/extension headers are used) */
 	REDUCE_FRAG_LEN(frag_len, (src->get_family(src) == AF_INET) ? 20 : 40);
diff --git a/src/libcharon/sa/ike_sa.c b/src/libcharon/sa/ike_sa.c
index c9b2a6c082..83865635d9 100644
--- a/src/libcharon/sa/ike_sa.c
+++ b/src/libcharon/sa/ike_sa.c
@@ -327,6 +327,30 @@ struct attribute_entry_t {
 	chunk_t data;
 };
 
+/**
+ * Determine the fragment size based on the address family of the remote host.
+ */
+static void determine_fragment_size(private_ike_sa_t *this)
+{
+	int family;
+
+	family = this->other_host->get_family(this->other_host);
+
+	this->fragment_size = lib->settings->get_int(lib->settings,
+			"%s.fragment_size_v%hhu", 0, lib->ns, (family == AF_INET ? 4 : 6));
+
+	if (!this->fragment_size)
+	{
+		this->fragment_size = lib->settings->get_int(lib->settings,
+			"%s.fragment_size", 1280, lib->ns);
+	}
+
+	if (!this->fragment_size)
+	{
+		this->fragment_size = (family == AF_INET) ? 576 : 1280;
+	}
+}
+
 /**
  * get the time of the latest traffic processed by the kernel
  */
@@ -415,6 +439,7 @@ METHOD(ike_sa_t, set_other_host, void,
 {
 	DESTROY_IF(this->other_host);
 	this->other_host = other;
+	determine_fragment_size(this);
 }
 
 METHOD(ike_sa_t, get_redirected_from, host_t*,
@@ -2908,14 +2933,10 @@ METHOD(ike_sa_t, inherit_post, void,
 	host_t *vip;
 
 	/* apply hosts and ids */
-	this->my_host->destroy(this->my_host);
-	this->other_host->destroy(this->other_host);
-	this->my_id->destroy(this->my_id);
-	this->other_id->destroy(this->other_id);
-	this->my_host = other->my_host->clone(other->my_host);
-	this->other_host = other->other_host->clone(other->other_host);
-	this->my_id = other->my_id->clone(other->my_id);
-	this->other_id = other->other_id->clone(other->other_id);
+	set_my_host(this, other->my_host->clone(other->my_host));
+	set_other_host(this, other->other_host->clone(other->other_host));
+	set_my_id(this, other->my_id->clone(other->my_id));
+	set_other_id(this, other->other_id->clone(other->other_id));
 	this->if_id_in = other->if_id_in;
 	this->if_id_out = other->if_id_out;
 
@@ -3228,8 +3249,6 @@ ike_sa_t * ike_sa_create(ike_sa_id_t *ike_sa_id, bool initiator,
 								"%s.retry_initiate_interval", 0, lib->ns),
 		.flush_auth_cfg = lib->settings->get_bool(lib->settings,
 								"%s.flush_auth_cfg", FALSE, lib->ns),
-		.fragment_size = lib->settings->get_int(lib->settings,
-								"%s.fragment_size", 1280, lib->ns),
 		.follow_redirects = lib->settings->get_bool(lib->settings,
 								"%s.follow_redirects", TRUE, lib->ns),
 	);