diff --git a/src/wasm/ast-decoder.cc b/src/wasm/ast-decoder.cc
index 40d4a0bac625..48db8e9e6808 100644
--- a/src/wasm/ast-decoder.cc
+++ b/src/wasm/ast-decoder.cc
@@ -509,7 +509,7 @@ class WasmFullDecoder : public WasmDecoder {
     }
 
     if (ssa_env_->go()) {
-      TRACE("  @%-6d #xx:%-20s|", startrel(pc_), "ImplicitReturn");
+      TRACE("  @%-8d #xx:%-20s|", startrel(pc_), "ImplicitReturn");
       DoReturn();
       if (failed()) return TraceFailed();
       TRACE("\n");
@@ -707,8 +707,10 @@ class WasmFullDecoder : public WasmDecoder {
     while (true) {  // decoding loop.
       unsigned len = 1;
       WasmOpcode opcode = static_cast<WasmOpcode>(*pc_);
-      TRACE("  @%-6d #%02x:%-20s|", startrel(pc_), opcode,
-            WasmOpcodes::ShortOpcodeName(opcode));
+      if (!WasmOpcodes::IsPrefixOpcode(opcode)) {
+        TRACE("  @%-8d #%02x:%-20s|", startrel(pc_), opcode,
+              WasmOpcodes::ShortOpcodeName(opcode));
+      }
 
       FunctionSig* sig = WasmOpcodes::Signature(opcode);
       if (sig) {
@@ -1271,6 +1273,8 @@ class WasmFullDecoder : public WasmDecoder {
             len++;
             byte simd_index = *(pc_ + 1);
             opcode = static_cast<WasmOpcode>(opcode << 8 | simd_index);
+            TRACE("  @%-4d #%02x #%02x:%-20s|", startrel(pc_), kSimdPrefix,
+                  simd_index, WasmOpcodes::ShortOpcodeName(opcode));
             DecodeSimdOpcode(opcode);
             break;
           }
@@ -1285,6 +1289,9 @@ class WasmFullDecoder : public WasmDecoder {
         for (size_t i = 0; i < stack_.size(); ++i) {
           Value& val = stack_[i];
           WasmOpcode opcode = static_cast<WasmOpcode>(*val.pc);
+          if (WasmOpcodes::IsPrefixOpcode(opcode)) {
+            opcode = static_cast<WasmOpcode>(opcode << 8 | *(val.pc + 1));
+          }
           PrintF(" %c@%d:%s", WasmOpcodes::ShortNameOf(val.type),
                  static_cast<int>(val.pc - start_),
                  WasmOpcodes::ShortOpcodeName(opcode));
diff --git a/src/wasm/wasm-opcodes.cc b/src/wasm/wasm-opcodes.cc
index 8f5420766136..3bffa60a7b8e 100644
--- a/src/wasm/wasm-opcodes.cc
+++ b/src/wasm/wasm-opcodes.cc
@@ -38,6 +38,18 @@ const char* WasmOpcodes::ShortOpcodeName(WasmOpcode opcode) {
   return "Unknown";
 }
 
+bool WasmOpcodes::IsPrefixOpcode(WasmOpcode opcode) {
+  switch (opcode) {
+#define CHECK_PREFIX(name, opcode) \
+  case k##name##Prefix:            \
+    return true;
+    FOREACH_PREFIX(CHECK_PREFIX)
+#undef CHECK_PREFIX
+    default:
+      return false;
+  }
+}
+
 std::ostream& operator<<(std::ostream& os, const FunctionSig& sig) {
   if (sig.return_count() == 0) os << "v";
   for (size_t i = 0; i < sig.return_count(); ++i) {
diff --git a/src/wasm/wasm-opcodes.h b/src/wasm/wasm-opcodes.h
index 1412587097e5..77c2c46633c2 100644
--- a/src/wasm/wasm-opcodes.h
+++ b/src/wasm/wasm-opcodes.h
@@ -489,6 +489,7 @@ class WasmOpcodes {
   static const char* OpcodeName(WasmOpcode opcode);
   static const char* ShortOpcodeName(WasmOpcode opcode);
   static FunctionSig* Signature(WasmOpcode opcode);
+  static bool IsPrefixOpcode(WasmOpcode opcode);
 
   static int TrapReasonToMessageId(TrapReason reason);
   static const char* TrapReasonMessage(TrapReason reason);