diff --git a/src/arch/x86/isa/decoder/two_byte_opcodes.isa b/src/arch/x86/isa/decoder/two_byte_opcodes.isa
index 4ebe03d84..064f5ce86 100644
--- a/src/arch/x86/isa/decoder/two_byte_opcodes.isa
+++ b/src/arch/x86/isa/decoder/two_byte_opcodes.isa
@@ -915,7 +915,11 @@
                     default: Inst::UD2();
                 }
             }
-            0x19: bswap_B();
+            0x19: decode OPSIZE {
+                4: Inst::BSWAP_D(Bd);
+                8: Inst::BSWAP_Q(Bq);
+                default: Inst::UD2();
+            }
             0x1A: decode LEGACY_DECODEVAL {
                 // no prefix
                 0x0: decode OPCODE_OP_BOTTOM3 {
diff --git a/src/arch/x86/isa/insts/general_purpose/data_conversion/endian_conversion.py b/src/arch/x86/isa/insts/general_purpose/data_conversion/endian_conversion.py
index b375ac27e..ac2343462 100644
--- a/src/arch/x86/isa/insts/general_purpose/data_conversion/endian_conversion.py
+++ b/src/arch/x86/isa/insts/general_purpose/data_conversion/endian_conversion.py
@@ -53,7 +53,25 @@
 #
 # Authors: Gabe Black
 
-microcode = ""
+microcode = '''
+def macroop BSWAP_D_R
+{
+    roli reg, reg, 8, dataSize=2
+    roli reg, reg, 16, dataSize=4
+    roli reg, reg, 8, dataSize=2
+};
+
+def macroop BSWAP_Q_R
+{
+    roli reg, reg, 8, dataSize=2
+    roli reg, reg, 16, dataSize=4
+    roli reg, reg, 8, dataSize=2
+    roli reg, reg, 32, dataSize=8
+    roli reg, reg, 8, dataSize=2
+    roli reg, reg, 16, dataSize=4
+    roli reg, reg, 8, dataSize=2
+};
+'''
 #let {{
 #    class BSWAP(Inst):
 #       "GenFault ${new UnimpInstFault}"