diff --git a/README.md b/README.md
index de771b9..7a20a9a 100644
--- a/README.md
+++ b/README.md
@@ -168,6 +168,7 @@ are appreciated. It really is keeping me motivated to continue development.
 
 - Maintenance. Updated all dependencies to the latest versions.
 - Bugfix: Fixed condition code for `asr/lsr/lsl`, which is has a different behaviour for V flag than `asl`.
+- Bugfix: Fixed 'Unknown op size' exception when uppercase sizes were used.
 
 ### V0.8 (15-Oct-21)
 
diff --git a/build.gradle b/build.gradle
index ba788dc..8e6957a 100644
--- a/build.gradle
+++ b/build.gradle
@@ -62,6 +62,7 @@ patchPluginXml {
     <ul>
     <li>Maintenance. Updated all dependencies to the latest versions.
     <li>Bugfix: Fixed condition code for asr/lsr/lsl, which is has a different behaviour for V flag than asl.
+    <li>Bugfix: Fixed 'Unknown op size' exception when uppercase sizes were used.
     </ul>
   <p>Full changelog available at <a href="https://github.com/chrisly42/mc68000-asm-plugin#changelog">Github project site</a>.</p>
 """)
diff --git a/src/main/java/de/platon42/intellij/plugins/m68k/psi/M68kPsiImplUtil.kt b/src/main/java/de/platon42/intellij/plugins/m68k/psi/M68kPsiImplUtil.kt
index eaa91a7..9658470 100644
--- a/src/main/java/de/platon42/intellij/plugins/m68k/psi/M68kPsiImplUtil.kt
+++ b/src/main/java/de/platon42/intellij/plugins/m68k/psi/M68kPsiImplUtil.kt
@@ -105,7 +105,7 @@ object M68kPsiImplUtil {
     // OperandSize
     @JvmStatic
     fun getSize(element: M68kOperandSize): Int =
-        when (element.text) {
+        when (element.text?.lowercase()) {
             null -> OP_UNSIZED
             ".w" -> OP_SIZE_W
             ".l" -> OP_SIZE_L
diff --git a/src/test/java/de/platon42/intellij/plugins/m68k/parser/AddressingModesTest.kt b/src/test/java/de/platon42/intellij/plugins/m68k/parser/AddressingModesTest.kt
index 11fec05..c1974a5 100644
--- a/src/test/java/de/platon42/intellij/plugins/m68k/parser/AddressingModesTest.kt
+++ b/src/test/java/de/platon42/intellij/plugins/m68k/parser/AddressingModesTest.kt
@@ -14,7 +14,7 @@ internal class AddressingModesTest : AbstractParsingTest() {
 
     @Test
     internal fun register_direct(@MyTestCase testCase: ParsingTestExtension.IParsingTestCase) {
-        testGoodSyntax(testCase, " move.l d0,a7\n")
+        testGoodSyntax(testCase, " MOVE.L d0,a7\n")
     }
 
     @Test
diff --git a/src/test/resources/parser/addressingmodes/register_direct.txt b/src/test/resources/parser/addressingmodes/register_direct.txt
index 6fb81e9..f5d7610 100644
--- a/src/test/resources/parser/addressingmodes/register_direct.txt
+++ b/src/test/resources/parser/addressingmodes/register_direct.txt
@@ -3,9 +3,9 @@ Assembly File: a.asm
   M68kStatementImpl(STATEMENT)
     M68kAsmInstructionImpl(ASM_INSTRUCTION)
       M68kAsmOpImpl(ASM_OP)
-        PsiElement(M68kTokenType.MNEMONIC)('move')
+        PsiElement(M68kTokenType.MNEMONIC)('MOVE')
         M68kOperandSizeImpl(OPERAND_SIZE)
-          PsiElement(M68kTokenType.OPSIZE_L)('.l')
+          PsiElement(M68kTokenType.OPSIZE_L)('.L')
       PsiWhiteSpace(' ')
       M68kDataRegisterDirectAddressingModeImpl(DATA_REGISTER_DIRECT_ADDRESSING_MODE)
         M68kDataRegisterImpl(DATA_REGISTER)