diff --git a/src/northbridge/intel/fsp_sandybridge/acpi.c b/src/northbridge/intel/fsp_sandybridge/acpi.c
index 3e47ed428b..faef4d71f9 100644
--- a/src/northbridge/intel/fsp_sandybridge/acpi.c
+++ b/src/northbridge/intel/fsp_sandybridge/acpi.c
@@ -142,7 +142,7 @@ int init_igd_opregion(igd_opregion_t *opregion)
 	// FIXME if IGD is disabled, we should exit here.
 
 	memcpy(&opregion->header.signature, IGD_OPREGION_SIGNATURE,
-		sizeof(IGD_OPREGION_SIGNATURE));
+		sizeof(opregion->header.signature));
 
 	/* 8kb */
 	opregion->header.size = sizeof(igd_opregion_t) / 1024;
diff --git a/src/northbridge/intel/haswell/acpi.c b/src/northbridge/intel/haswell/acpi.c
index 964a9d3b5f..b2fab11e58 100644
--- a/src/northbridge/intel/haswell/acpi.c
+++ b/src/northbridge/intel/haswell/acpi.c
@@ -140,7 +140,7 @@ int init_igd_opregion(igd_opregion_t *opregion)
 	// FIXME if IGD is disabled, we should exit here.
 
 	memcpy(&opregion->header.signature, IGD_OPREGION_SIGNATURE,
-		sizeof(IGD_OPREGION_SIGNATURE));
+		sizeof(opregion->header.signature));
 
 	/* 8kb */
 	opregion->header.size = sizeof(igd_opregion_t) / 1024;
diff --git a/src/northbridge/intel/nehalem/acpi.c b/src/northbridge/intel/nehalem/acpi.c
index 077cedaa95..0ede2376e4 100644
--- a/src/northbridge/intel/nehalem/acpi.c
+++ b/src/northbridge/intel/nehalem/acpi.c
@@ -139,7 +139,7 @@ int init_igd_opregion(igd_opregion_t * opregion)
 	// FIXME if IGD is disabled, we should exit here.
 
 	memcpy(&opregion->header.signature, IGD_OPREGION_SIGNATURE,
-	       sizeof(IGD_OPREGION_SIGNATURE));
+		sizeof(opregion->header.signature));
 
 	/* 8kb */
 	opregion->header.size = sizeof(igd_opregion_t) / 1024;
diff --git a/src/northbridge/intel/sandybridge/acpi.c b/src/northbridge/intel/sandybridge/acpi.c
index 398cb308f7..58e3b544f5 100644
--- a/src/northbridge/intel/sandybridge/acpi.c
+++ b/src/northbridge/intel/sandybridge/acpi.c
@@ -142,7 +142,7 @@ int init_igd_opregion(igd_opregion_t *opregion)
 	// FIXME if IGD is disabled, we should exit here.
 
 	memcpy(&opregion->header.signature, IGD_OPREGION_SIGNATURE,
-		sizeof(IGD_OPREGION_SIGNATURE));
+		sizeof(opregion->header.signature));
 
 	/* 8kb */
 	opregion->header.size = sizeof(igd_opregion_t) / 1024;