diff --git a/arch/s390/kernel/dis.c b/arch/s390/kernel/dis.c
index 3be829721cf9..465d52b5e470 100644
--- a/arch/s390/kernel/dis.c
+++ b/arch/s390/kernel/dis.c
@@ -396,9 +396,14 @@ struct s390_insn *find_insn(unsigned char *code)
 	unsigned char opfrag;
 	int i;
 
+	/* Search the opcode offset table to find an entry which
+	 * matches the beginning of the opcode. If there is no match
+	 * the last entry will be used, which is the default entry for
+	 * unknown instructions as well as 1-byte opcode instructions.
+	 */
 	for (i = 0; i < ARRAY_SIZE(opcode_offset); i++) {
 		entry = &opcode_offset[i];
-		if (entry->opcode == code[0] || entry->opcode == 0)
+		if (entry->opcode == code[0])
 			break;
 	}