diff --git a/src/include/lib/lib_13130.h b/src/include/lib/lib_13130.h
index 07cccd3f0..7d76d428a 100644
--- a/src/include/lib/lib_13130.h
+++ b/src/include/lib/lib_13130.h
@@ -10,7 +10,7 @@ s32 strcmp(char *a, char *b);
 u32 func000132c0(void);
 char toupper(char c);
 s32 isdigit(char c);
-u32 func00013378(void);
+s32 isalpha(char c);
 u32 func000133b4(void);
 s32 func00013408(char *arg0, s32 *arg1, s32 arg2);
 int sprintf(char *dest, const char *format, ...);
diff --git a/src/lib/lib_13130.c b/src/lib/lib_13130.c
index 58f59877a..1f50717a3 100644
--- a/src/lib/lib_13130.c
+++ b/src/lib/lib_13130.c
@@ -199,26 +199,10 @@ s32 isdigit(char c)
 	return c >= '0' && c <= '9';
 }
 
-GLOBAL_ASM(
-glabel func00013378
-/*    13378:	308e00ff */ 	andi	$t6,$a0,0xff
-/*    1337c:	29c20061 */ 	slti	$v0,$t6,0x61
-/*    13380:	afa40000 */ 	sw	$a0,0x0($sp)
-/*    13384:	14400004 */ 	bnez	$v0,.L00013398
-/*    13388:	01c01825 */ 	or	$v1,$t6,$zero
-/*    1338c:	29c2007b */ 	slti	$v0,$t6,0x7b
-/*    13390:	14400006 */ 	bnez	$v0,.L000133ac
-/*    13394:	00000000 */ 	nop
-.L00013398:
-/*    13398:	28620041 */ 	slti	$v0,$v1,0x41
-/*    1339c:	38420001 */ 	xori	$v0,$v0,0x1
-/*    133a0:	10400002 */ 	beqz	$v0,.L000133ac
-/*    133a4:	00000000 */ 	nop
-/*    133a8:	2862005b */ 	slti	$v0,$v1,0x5b
-.L000133ac:
-/*    133ac:	03e00008 */ 	jr	$ra
-/*    133b0:	00000000 */ 	nop
-);
+s32 isalpha(char c)
+{
+	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
+}
 
 GLOBAL_ASM(
 glabel func000133b4
@@ -347,7 +331,7 @@ glabel func00013408
 /*    13560:	1000000a */ 	b	.L0001358c
 /*    13564:	03008025 */ 	or	$s0,$t8,$zero
 .L00013568:
-/*    13568:	0c004cde */ 	jal	func00013378
+/*    13568:	0c004cde */ 	jal	isalpha
 /*    1356c:	320400ff */ 	andi	$a0,$s0,0xff
 /*    13570:	50400026 */ 	beqzl	$v0,.L0001360c
 /*    13574:	8faa0044 */ 	lw	$t2,0x44($sp)