diff --git a/lib/cpus/aarch64/cortex_x3.S b/lib/cpus/aarch64/cortex_x3.S
index 0cb3b97..95f3d10 100644
--- a/lib/cpus/aarch64/cortex_x3.S
+++ b/lib/cpus/aarch64/cortex_x3.S
@@ -57,6 +57,13 @@
 
 check_erratum_ls cortex_x3, ERRATUM(2742421), CPU_REV(1, 1)
 
+workaround_reset_start cortex_x3, ERRATUM(2779509), ERRATA_X3_2779509
+	/* Set CPUACTLR3_EL1 bit 47 */
+	sysreg_bit_set CORTEX_X3_CPUACTLR3_EL1, CORTEX_X3_CPUACTLR3_EL1_BIT_47
+workaround_reset_end cortex_x3, ERRATUM(2779509)
+
+check_erratum_ls cortex_x3, ERRATUM(2779509), CPU_REV(1, 1)
+
 workaround_reset_start cortex_x3, CVE(2022, 23960), WORKAROUND_CVE_2022_23960
 #if IMAGE_BL31
 	override_vector_table wa_cve_vbar_cortex_x3
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 434ee08..283314b 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -769,6 +769,10 @@
 # to revisions r0p0, r1p0 and r1p1 of the Cortex-X3 cpu, it is fixed in r1p2.
 CPU_FLAG_LIST += ERRATA_X3_2742421
 
+# Flag to apply erratum 2779509 workaround on reset. This erratum applies
+# to revisions r0p0, r1p0, r1p1 of the Cortex-X3 cpu, it is fixed in r1p2.
+CPU_FLAG_LIST += ERRATA_X3_2779509
+
 # Flag to apply erratum 1922240 workaround during reset. This erratum applies
 # to revision r0p0 of the Cortex-A510 cpu and is fixed in r0p1.
 CPU_FLAG_LIST += ERRATA_A510_1922240