diff --git a/isisd/isis_errors.c b/isisd/isis_errors.c
index 7530d0b966fe..1d277ac5f1c4 100644
--- a/isisd/isis_errors.c
+++ b/isisd/isis_errors.c
@@ -43,6 +43,12 @@ static struct log_ref ferr_isis_err[] = {
 		.description = "Isis has detected that a SID index falls outside of its associated SRGB range",
 		.suggestion = "Configure a larger SRGB"
 	},
+	{
+		.code = EC_ISIS_SID_COLLISION,
+		.title = "SID collision",
+		.description = "Isis has detected that two different prefixes share the same SID index",
+		.suggestion = "Identify the routers that are advertising the same SID index and fix the collision accordingly"
+	},
 	{
 		.code = END_FERR,
 	}
diff --git a/isisd/isis_errors.h b/isisd/isis_errors.h
index d5674dbf3021..6f3e5f85cfa1 100644
--- a/isisd/isis_errors.h
+++ b/isisd/isis_errors.h
@@ -27,6 +27,7 @@ enum isis_log_refs {
 	EC_ISIS_PACKET = ISIS_FERR_START,
 	EC_ISIS_CONFIG,
 	EC_ISIS_SID_OVERFLOW,
+	EC_ISIS_SID_COLLISION,
 };
 
 extern void isis_error_init(void);
diff --git a/isisd/isis_nb_config.c b/isisd/isis_nb_config.c
index 6cb7d32c25dd..c1cb2eceeeea 100644
--- a/isisd/isis_nb_config.c
+++ b/isisd/isis_nb_config.c
@@ -22,6 +22,7 @@
 
 #include <zebra.h>
 
+#include "printfrr.h"
 #include "northbound.h"
 #include "linklist.h"
 #include "log.h"
@@ -1739,12 +1740,17 @@ int isis_instance_segment_routing_prefix_sid_map_prefix_sid_destroy(
 int isis_instance_segment_routing_prefix_sid_map_prefix_sid_pre_validate(
 	struct nb_cb_pre_validate_args *args)
 {
+	const struct lyd_node *area_dnode;
+	struct isis_area *area;
+	struct prefix prefix;
 	uint32_t srgb_lbound;
 	uint32_t srgb_ubound;
 	uint32_t srgb_range;
 	uint32_t sid;
 	enum sr_sid_value_type sid_type;
+	struct isis_prefix_sid psid = {};
 
+	yang_dnode_get_prefix(&prefix, args->dnode, "./prefix");
 	srgb_lbound = yang_dnode_get_uint32(args->dnode,
 					    "../../srgb/lower-bound");
 	srgb_ubound = yang_dnode_get_uint32(args->dnode,
@@ -1752,7 +1758,9 @@ int isis_instance_segment_routing_prefix_sid_map_prefix_sid_pre_validate(
 	sid = yang_dnode_get_uint32(args->dnode, "./sid-value");
 	sid_type = yang_dnode_get_enum(args->dnode, "./sid-value-type");
 
+	/* Check for invalid indexes/labels. */
 	srgb_range = srgb_ubound - srgb_lbound + 1;
+	psid.value = sid;
 	switch (sid_type) {
 	case SR_SID_VALUE_TYPE_INDEX:
 		if (sid >= srgb_range) {
@@ -1766,9 +1774,49 @@ int isis_instance_segment_routing_prefix_sid_map_prefix_sid_pre_validate(
 			zlog_warn("Invalid absolute SID %u", sid);
 			return NB_ERR_VALIDATION;
 		}
+		SET_FLAG(psid.flags, ISIS_PREFIX_SID_VALUE);
+		SET_FLAG(psid.flags, ISIS_PREFIX_SID_LOCAL);
 		break;
 	}
 
+	/* Check for Prefix-SID collisions. */
+	area_dnode = yang_dnode_get_parent(args->dnode, "instance");
+	area = nb_running_get_entry(area_dnode, NULL, false);
+	if (area) {
+		for (int tree = SPFTREE_IPV4; tree < SPFTREE_COUNT; tree++) {
+			for (int level = ISIS_LEVEL1; level <= ISIS_LEVEL2;
+			     level++) {
+				struct isis_spftree *spftree;
+				struct isis_vertex *vertex_psid;
+
+				if (!(area->is_type & level))
+					continue;
+				spftree = area->spftree[tree][level - 1];
+				if (!spftree)
+					continue;
+
+				vertex_psid = isis_spf_prefix_sid_lookup(
+					spftree, &psid);
+				if (vertex_psid
+				    && !prefix_same(&vertex_psid->N.ip.p.dest,
+						    &prefix)) {
+					snprintfrr(
+						args->errmsg, args->errmsg_len,
+						"Prefix-SID collision detected, SID %s %u is already in use by prefix %pFX (L%u)",
+						CHECK_FLAG(
+							psid.flags,
+							ISIS_PREFIX_SID_VALUE)
+							? "label"
+							: "index",
+						psid.value,
+						&vertex_psid->N.ip.p.dest,
+						level);
+					return NB_ERR_VALIDATION;
+				}
+			}
+		}
+	}
+
 	return NB_OK;
 }
 
diff --git a/isisd/isis_spf.c b/isisd/isis_spf.c
index 690ea9f1a5e8..5480a1b3394f 100644
--- a/isisd/isis_spf.c
+++ b/isisd/isis_spf.c
@@ -33,11 +33,13 @@
 #include "memory.h"
 #include "prefix.h"
 #include "if.h"
+#include "hash.h"
 #include "table.h"
 #include "spf_backoff.h"
 #include "srcdest_table.h"
 #include "vrf.h"
 
+#include "isis_errors.h"
 #include "isis_constants.h"
 #include "isis_common.h"
 #include "isis_flags.h"
@@ -184,6 +186,36 @@ const char *vid2string(const struct isis_vertex *vertex, char *buff, int size)
 	return "UNKNOWN";
 }
 
+static bool prefix_sid_cmp(const void *value1, const void *value2)
+{
+	const struct isis_vertex *c1 = value1;
+	const struct isis_vertex *c2 = value2;
+
+	if (CHECK_FLAG(c1->N.ip.sr.sid.flags,
+		       ISIS_PREFIX_SID_VALUE | ISIS_PREFIX_SID_LOCAL)
+	    != CHECK_FLAG(c2->N.ip.sr.sid.flags,
+			  ISIS_PREFIX_SID_VALUE | ISIS_PREFIX_SID_LOCAL))
+		return false;
+
+	return c1->N.ip.sr.sid.value == c2->N.ip.sr.sid.value;
+}
+
+static unsigned int prefix_sid_key_make(const void *value)
+{
+	const struct isis_vertex *vertex = value;
+
+	return jhash_1word(vertex->N.ip.sr.sid.value, 0);
+}
+
+struct isis_vertex *isis_spf_prefix_sid_lookup(struct isis_spftree *spftree,
+					       struct isis_prefix_sid *psid)
+{
+	struct isis_vertex lookup = {};
+
+	lookup.N.ip.sr.sid = *psid;
+	return hash_lookup(spftree->prefix_sids, &lookup);
+}
+
 static void isis_vertex_adj_free(void *arg)
 {
 	struct isis_vertex_adj *vadj = arg;
@@ -310,6 +342,8 @@ struct isis_spftree *isis_spftree_new(struct isis_area *area,
 	tree->route_table_backup->cleanup = isis_route_node_cleanup;
 	tree->area = area;
 	tree->lspdb = lspdb;
+	tree->prefix_sids = hash_create(prefix_sid_key_make, prefix_sid_cmp,
+					"SR Prefix-SID Entries");
 	tree->sadj_list = list_new();
 	tree->sadj_list->del = isis_spf_adj_free;
 	tree->last_run_timestamp = 0;
@@ -332,6 +366,8 @@ struct isis_spftree *isis_spftree_new(struct isis_area *area,
 
 void isis_spftree_del(struct isis_spftree *spftree)
 {
+	hash_clean(spftree->prefix_sids, NULL);
+	hash_free(spftree->prefix_sids);
 	if (spftree->type == SPF_TYPE_TI_LFA) {
 		isis_spf_node_list_clear(&spftree->lfa.q_space);
 		isis_spf_node_list_clear(&spftree->lfa.p_space);
@@ -515,14 +551,39 @@ isis_spf_add2tent(struct isis_spftree *spftree, enum vertextype vtype, void *id,
 	vertex->d_N = cost;
 	vertex->depth = depth;
 	if (VTYPE_IP(vtype) && psid) {
-		bool local;
+		struct isis_area *area = spftree->area;
+		struct isis_vertex *vertex_psid;
 
-		local = (vertex->depth == 1);
-		vertex->N.ip.sr.sid = *psid;
-		vertex->N.ip.sr.label =
-			sr_prefix_in_label(spftree->area, psid, local);
-		if (vertex->N.ip.sr.label != MPLS_INVALID_LABEL)
-			vertex->N.ip.sr.present = true;
+		/*
+		 * Check if the Prefix-SID is already in use by another prefix.
+		 */
+		vertex_psid = isis_spf_prefix_sid_lookup(spftree, psid);
+		if (vertex_psid
+		    && !prefix_same(&vertex_psid->N.ip.p.dest,
+				    &vertex->N.ip.p.dest)) {
+			flog_warn(
+				EC_ISIS_SID_COLLISION,
+				"ISIS-Sr (%s): collision detected, prefixes %pFX and %pFX share the same SID %s (%u)",
+				area->area_tag, &vertex->N.ip.p.dest,
+				&vertex_psid->N.ip.p.dest,
+				CHECK_FLAG(psid->flags, ISIS_PREFIX_SID_VALUE)
+					? "label"
+					: "index",
+				psid->value);
+			psid = NULL;
+		} else {
+			bool local;
+
+			local = (vertex->depth == 1);
+			vertex->N.ip.sr.sid = *psid;
+			vertex->N.ip.sr.label =
+				sr_prefix_in_label(area, psid, local);
+			if (vertex->N.ip.sr.label != MPLS_INVALID_LABEL)
+				vertex->N.ip.sr.present = true;
+
+			hash_get(spftree->prefix_sids, vertex,
+				 hash_alloc_intern);
+		}
 	}
 
 	if (parent) {
@@ -1352,6 +1413,7 @@ static void add_to_paths(struct isis_spftree *spftree,
 static void init_spt(struct isis_spftree *spftree, int mtid)
 {
 	/* Clear data from previous run. */
+	hash_clean(spftree->prefix_sids, NULL);
 	isis_spf_node_list_clear(&spftree->adj_nodes);
 	list_delete_all_node(spftree->sadj_list);
 	isis_vertex_queue_clear(&spftree->tents);
diff --git a/isisd/isis_spf.h b/isisd/isis_spf.h
index 15d3ff927278..a9a14fc75e58 100644
--- a/isisd/isis_spf.h
+++ b/isisd/isis_spf.h
@@ -53,6 +53,8 @@ struct isis_spftree *isis_spftree_new(struct isis_area *area,
 				      const uint8_t *sysid, int level,
 				      enum spf_tree_id tree_id,
 				      enum spf_type type, uint8_t flags);
+struct isis_vertex *isis_spf_prefix_sid_lookup(struct isis_spftree *spftree,
+					       struct isis_prefix_sid *psid);
 void isis_spf_invalidate_routes(struct isis_spftree *tree);
 void isis_spf_verify_routes(struct isis_area *area,
 			    struct isis_spftree **trees);
diff --git a/isisd/isis_spf_private.h b/isisd/isis_spf_private.h
index e999f9653969..9cb1a39b8272 100644
--- a/isisd/isis_spf_private.h
+++ b/isisd/isis_spf_private.h
@@ -313,6 +313,7 @@ struct isis_spftree {
 	struct route_table *route_table;
 	struct route_table *route_table_backup;
 	struct lspdb_head *lspdb; /* link-state db */
+	struct hash *prefix_sids; /* SR Prefix-SIDs. */
 	struct list *sadj_list;
 	struct isis_spf_nodes adj_nodes;
 	struct isis_area *area;    /* back pointer to area */