diff --git a/src/x64/disasm-x64.cc b/src/x64/disasm-x64.cc
index 547daee..bd912cd 100644
--- a/src/x64/disasm-x64.cc
+++ b/src/x64/disasm-x64.cc
@@ -996,19 +996,45 @@
   if (operand_size_ == 0x66) {
     // 0x66 0x0F prefix.
     int mod, regop, rm;
-    get_modrm(*current, &mod, &regop, &rm);
-    const char* mnemonic = "?";
-    if (opcode == 0x57) {
-      mnemonic = "xorpd";
-    } else if (opcode == 0x2E) {
-      mnemonic = "comisd";
-    } else if (opcode == 0x2F) {
-      mnemonic = "ucomisd";
+    if (opcode == 0x3A) {
+      byte third_byte = *current;
+      current = data + 3;
+      if (third_byte == 0x17) {
+        get_modrm(*current, &mod, &regop, &rm);
+        AppendToBuffer("extractps ");  // reg/m32, xmm, imm8
+        current += PrintRightOperand(current);
+        AppendToBuffer(", %s, %d", NameOfCPURegister(regop), (*current) & 3);
+        current += 1;
+      } else {
+        UnimplementedInstruction();
+      }
     } else {
-      UnimplementedInstruction();
+      get_modrm(*current, &mod, &regop, &rm);
+      if (opcode == 0x6E) {
+        AppendToBuffer("mov%c %s,",
+                       rex_w() ? 'q' : 'd',
+                       NameOfXMMRegister(regop));
+        current += PrintRightOperand(current);
+      } else if (opcode == 0x7E) {
+        AppendToBuffer("mov%c %s,",
+                       rex_w() ? 'q' : 'd',
+                       NameOfCPURegister(regop));
+        current += PrintRightXMMOperand(current);
+      } else {
+        const char* mnemonic = "?";
+        if (opcode == 0x57) {
+          mnemonic = "xorpd";
+        } else if (opcode == 0x2E) {
+          mnemonic = "comisd";
+        } else if (opcode == 0x2F) {
+          mnemonic = "ucomisd";
+        } else {
+          UnimplementedInstruction();
+        }
+        AppendToBuffer("%s %s,", mnemonic, NameOfXMMRegister(regop));
+        current += PrintRightXMMOperand(current);
+      }
     }
-    AppendToBuffer("%s %s,", mnemonic, NameOfXMMRegister(regop));
-    current += PrintRightXMMOperand(current);
   } else if (group_1_prefix_ == 0xF2) {
     // Beginning of instructions with prefix 0xF2.
 
@@ -1030,7 +1056,7 @@
       get_modrm(*current, &mod, &regop, &rm);
       AppendToBuffer("%s %s,", mnemonic, NameOfXMMRegister(regop));
       current += PrintRightOperand(current);
-    } else if ((opcode & 0xF8) == 0x58) {
+    } else if ((opcode & 0xF8) == 0x58 || opcode == 0x51) {
       // XMM arithmetic. Mnemonic was retrieved at the start of this function.
       int mod, regop, rm;
       get_modrm(*current, &mod, &regop, &rm);
@@ -1039,13 +1065,21 @@
     } else {
       UnimplementedInstruction();
     }
-  } else if (opcode == 0x2C && group_1_prefix_ == 0xF3) {
-    // Instruction with prefix 0xF3.
-
-    // CVTTSS2SI: Convert scalar single-precision FP to dword integer.
-    // Assert that mod is not 3, so source is memory, not an XMM register.
-    ASSERT_NE(0xC0, *current & 0xC0);
-    current += PrintOperands("cvttss2si", REG_OPER_OP_ORDER, current);
+  } else if (group_1_prefix_ == 0xF3) {
+    // Instructions with prefix 0xF3.
+    if (opcode == 0x2C) {
+      // CVTTSS2SI: Convert scalar single-precision FP to dword integer.
+      // Assert that mod is not 3, so source is memory, not an XMM register.
+      ASSERT_NE(0xC0, *current & 0xC0);
+      current += PrintOperands("cvttss2si", REG_OPER_OP_ORDER, current);
+    } else if (opcode == 0x5A) {
+      int mod, regop, rm;
+      get_modrm(*current, &mod, &regop, &rm);
+      AppendToBuffer("cvtss2sd %s,", NameOfXMMRegister(regop));
+      current += PrintRightXMMOperand(current);
+    } else {
+      UnimplementedInstruction();
+    }
   } else if (opcode == 0x1F) {
     // NOP
     int mod, regop, rm;
@@ -1113,6 +1147,8 @@
       return "cvtsi2sd";
     case 0x31:
       return "rdtsc";
+    case 0x51:  // F2 prefix.
+      return "sqrtsd";
     case 0x58:  // F2 prefix.
       return "addsd";
     case 0x59:  // F2 prefix.
@@ -1273,7 +1309,9 @@
         get_modrm(*(data + 1), &mod, &regop, &rm);
         int32_t imm = *data == 0x6B ? *(data + 2)
             : *reinterpret_cast<int32_t*>(data + 2);
-        AppendToBuffer("imul %s,%s,0x%x", NameOfCPURegister(regop),
+        AppendToBuffer("imul%c %s,%s,0x%x",
+                       operand_size_code(),
+                       NameOfCPURegister(regop),
                        NameOfCPURegister(rm), imm);
         data += 2 + (*data == 0x6B ? 1 : 4);
         break;