diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index 3effb11c4153..19d194ff37ca 100644
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -358,7 +358,16 @@ static int acpi_pcc_retrieve_biosdata(struct pcc_acpi *pcc)
 		} else
 			pr_err("Invalid HKEY.SINF data\n");
 	}
-	pcc->sinf[hkey->package.count] = -1;
+	/*
+	 * pcc->sinf[] has pcc->num_sifr elements (valid indices
+	 * 0..num_sifr-1). On DSDTs where SINF's package count equals
+	 * num_sifr exactly -- the off-by-one case probe()'s num_sifr++
+	 * already allocates a spare element for -- there is no room left
+	 * for this trailing sentinel; nothing reads it back, so just skip
+	 * the write rather than running one element past the flex array.
+	 */
+	if (hkey->package.count < pcc->num_sifr)
+		pcc->sinf[hkey->package.count] = -1;
 
 end:
 	kfree(buffer.pointer);