diff --git a/app/src/main/kotlin/android/emu6502/Assembler.kt b/app/src/main/kotlin/android/emu6502/Assembler.kt
index bf5b741..ab936f3 100644
--- a/app/src/main/kotlin/android/emu6502/Assembler.kt
+++ b/app/src/main/kotlin/android/emu6502/Assembler.kt
@@ -234,7 +234,7 @@ class Assembler(private var memory: Memory, private val symbols: Symbols) {
       val finalParam = param.replace(",Y", "", true).replace(",X", "", true)
       pushByte(opcode)
       val addr = labels.get(finalParam)
-      if (addr != null) {
+      if (addr != -1) {
         if (addr < 0 || addr > 0xffff) {
           return false
         }
@@ -259,7 +259,7 @@ class Assembler(private var memory: Memory, private val symbols: Symbols) {
     if (opcode == 0xff) {
       return false
     }
-    return checkByteOperand(param, opcode, "^\\(([\\w\\$]+)\\),X$")
+    return checkByteOperand(param, opcode, "^\\(([\\w\\$]+),X\\)$")
   }
 
   private fun checkIndirect(param: String, opcode: Int): Boolean {
@@ -320,7 +320,7 @@ class Assembler(private var memory: Memory, private val symbols: Symbols) {
       var hilo = param.replace("^#([<>]).*$".toRegex(), "$1")
       pushByte(opcode)
       val addr = labels.get(label)
-      if (addr != null) {
+      if (addr != -1) {
         when (hilo) {
           ">" -> {
             pushByte(addr.shr(8).and(0xFF))
diff --git a/app/src/test/java/android/emu6502/AssemblerTest.java b/app/src/test/java/android/emu6502/AssemblerTest.java
index a50266c..0acee5f 100644
--- a/app/src/test/java/android/emu6502/AssemblerTest.java
+++ b/app/src/test/java/android/emu6502/AssemblerTest.java
@@ -82,7 +82,7 @@ public class AssemblerTest {
     assertThat(assembler.hexdump(), equalTo("0600: A9 01 85 F0 A9 CC 85 F1 6C F0 00"));
   }
 
-  @Test public void testIndexedIndirect() {
+  @Test public void testIndirectX() {
     List<String> lines = ImmutableList.of(
         "LDX #$01",
         "LDA #$05",
@@ -97,4 +97,34 @@ public class AssemblerTest {
     assertThat(assembler.hexdump(),
         equalTo("0600: A2 01 A9 05 85 01 A9 06 85 02 A0 0A 8C 05 06 A1 \n0610: 00"));
   }
+
+  @Test public void testIndirectY() {
+    List<String> lines = ImmutableList.of(
+        "LDY #$01",
+        "LDA #$03",
+        "STA $01",
+        "LDA #$07",
+        "STA $02",
+        "LDX #$0a",
+        "STX $0704",
+        "LDA ($01),Y");
+
+    assembler.assembleCode(lines);
+    assertThat(assembler.hexdump(),
+        equalTo("0600: A0 01 A9 03 85 01 A9 07 85 02 A2 0A 8E 04 07 B1 \n0610: 01"));
+  }
+
+  @Test public void testJump() {
+    List<String> lines = ImmutableList.of(
+        "LDA #$03",
+        "JMP there",
+        "BRK",
+        "BRK",
+        "BRK",
+        "there:",
+        "STA $0200");
+
+    assembler.assembleCode(lines);
+    assertThat(assembler.hexdump(), equalTo("0600: A9 03 4C 08 06 00 00 00 8D 00 02"));
+  }
 }