Index: lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp
===================================================================
--- lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp
+++ lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp
@@ -199,6 +199,7 @@
     case WebAssembly::OPERAND_OFFSET32:
     case WebAssembly::OPERAND_P2ALIGN:
     case WebAssembly::OPERAND_TYPEINDEX:
+    case WebAssembly::OPERAND_EVENT:
     case MCOI::OPERAND_IMMEDIATE: {
       if (!parseLEBImmediate(MI, Size, Bytes, false))
         return MCDisassembler::Fail;
Index: test/MC/Disassembler/WebAssembly/wasm.txt
===================================================================
--- test/MC/Disassembler/WebAssembly/wasm.txt
+++ test/MC/Disassembler/WebAssembly/wasm.txt
@@ -55,3 +55,6 @@
 # This can mean end_block/end_loop/end_if/end_function/end_try..
 # CHECK: end
 0x0B
+
+# CHECK: br_on_exn 0, 0
+0x0A 0x00 0x00