diff --git a/bdshemu/bdshemu.c b/bdshemu/bdshemu.c
index a52fdb0..6fa7862 100644
--- a/bdshemu/bdshemu.c
+++ b/bdshemu/bdshemu.c
@@ -250,24 +250,7 @@ ShemuCopyMem(
     ND_UINT64 Size
     )
 {
-    switch (Size)
-    {
-    case 1:
-        *Destination = *Source;
-        break;
-    case 2:
-        *(ND_UINT16 *)Destination = *(ND_UINT16 *)Source;
-        break;
-    case 4:
-        *(ND_UINT32 *)Destination = *(ND_UINT32 *)Source;
-        break;
-    case 8:
-        *(ND_UINT64 *)Destination = *(ND_UINT64 *)Source;
-        break;
-    default:
-        shemu_memcpy(Destination, Source, (ND_SIZET)Size);
-        break;
-    }
+    shemu_memcpy(Destination, Source, (ND_SIZET)Size);
 }
 
 
diff --git a/bdshemu/bdshemu_x86.c b/bdshemu/bdshemu_x86.c
index 21469d1..0ebed16 100644
--- a/bdshemu/bdshemu_x86.c
+++ b/bdshemu/bdshemu_x86.c
@@ -77,18 +77,18 @@ enum
 
 
 #define GET_OP(ctx, op, val) {                                                                                         \
-    SHEMU_STATUS status = ShemuX86GetOperandValue(ctx, op, val);                                                       \
-    if (SHEMU_SUCCESS != status)                                                                                       \
+    shstatus = ShemuX86GetOperandValue(ctx, op, val);                                                                  \
+    if (SHEMU_SUCCESS != shstatus)                                                                                     \
     {                                                                                                                  \
-        return status;                                                                                                 \
+        return shstatus;                                                                                               \
     }                                                                                                                  \
 }
 
 #define SET_OP(ctx, op, val) {                                                                                         \
-    SHEMU_STATUS status = ShemuX86SetOperandValue(ctx, op, val);                                                       \
-    if (SHEMU_SUCCESS != status)                                                                                       \
+    shstatus = ShemuX86SetOperandValue(ctx, op, val);                                                                  \
+    if (SHEMU_SUCCESS != shstatus)                                                                                     \
     {                                                                                                                  \
-        return status;                                                                                                 \
+        return shstatus;                                                                                               \
     }                                                                                                                  \
 }
 
@@ -1448,20 +1448,23 @@ ShemuX86Multiply64Unsigned(
     ND_UINT64 *ResLow
     )
 {
-    ND_UINT64 xLow = (ND_UINT64)(ND_UINT32)Operand1;
-    ND_UINT64 xHigh = Operand1 >> 32;
-    ND_UINT64 yLow = (ND_UINT64)(ND_UINT32)Operand2;
-    ND_UINT64 yHigh = Operand2 >> 32;
+    ND_UINT64 xLow, xHigh, yLow, yHigh, p0, p1, p2, p3, ps;
 
-    ND_UINT64 p0 = xLow * yLow;
-    ND_UINT64 p1 = xLow * yHigh;
-    ND_UINT64 p2 = xHigh * yLow;
-    ND_UINT64 p3 = xHigh * yHigh;
+    xLow = Operand1 & 0xFFFFFFFF;
+    xHigh = Operand1 >> 32;
+    yLow = Operand2 & 0xFFFFFFFF;
+    yHigh = Operand2 >> 32;
 
-    ND_UINT32 cy = (ND_UINT32)(((p0 >> 32) + (ND_UINT32)p1 + (ND_UINT32)p2) >> 32);
+    // Multiply the 4 parts into 4 partial products.
+    p0 = xLow * yLow;
+    p1 = xLow * yHigh;
+    p2 = xHigh * yLow;
+    p3 = xHigh * yHigh;
+    ps = (((p0 >> 32) + (p1 & 0xFFFFFFFF) + (p2 & 0xFFFFFFFF)) >> 32) & 0xFFFFFFFF;
 
+    // Fill in the final result (low & high 64-bit parts).
     *ResLow = p0 + (p1 << 32) + (p2 << 32);
-    *ResHigh = p3 + (p1 >> 32) + (p2 >> 32) + cy;
+    *ResHigh = p3 + (p1 >> 32) + (p2 >> 32) + ps;
 }
 
 
@@ -1477,8 +1480,18 @@ ShemuX86Multiply64Signed(
     )
 {
     ShemuX86Multiply64Unsigned((ND_UINT64)Operand1, (ND_UINT64)Operand2, (ND_UINT64 *)ResHigh, (ND_UINT64 *)ResLow);
-    if (Operand1 < 0LL) *ResHigh -= Operand2;
-    if (Operand2 < 0LL) *ResHigh -= Operand1;
+
+    // Negate, if needed.
+    if (Operand1 < 0)
+    {
+        *ResHigh -= Operand2;
+    }
+
+    // Negate, if needed.
+    if (Operand2 < 0)
+    {
+        *ResHigh -= Operand1;
+    }
 }
 
 
@@ -2789,7 +2802,7 @@ check_far_branch:
                 }
                 else
                 {
-                    ShemuX86Multiply64Signed(dst.Value.Qwords[0], src.Value.Qwords[0],
+                    ShemuX86Multiply64Signed((ND_SINT64)dst.Value.Qwords[0], (ND_SINT64)src.Value.Qwords[0],
                                           (ND_SINT64*)&res.Value.Qwords[1], (ND_SINT64*)&res.Value.Qwords[0]);
                 }
             }
diff --git a/inc/bdx86_registers.h b/inc/bdx86_registers.h
index 07db581..3904e3d 100644
--- a/inc/bdx86_registers.h
+++ b/inc/bdx86_registers.h
@@ -139,22 +139,22 @@ enum
 #define NDR_IA32_TSC_AUX                0xC0000103
 #define NDR_MSR_ANY                     0xFFFFFFFF
 
-#define NDR_RFLAG_CF                    (1 << 0)
-#define NDR_RFLAG_PF                    (1 << 2)
-#define NDR_RFLAG_AF                    (1 << 4)
-#define NDR_RFLAG_ZF                    (1 << 6)
-#define NDR_RFLAG_SF                    (1 << 7)
-#define NDR_RFLAG_TF                    (1 << 8)
-#define NDR_RFLAG_IF                    (1 << 9)
-#define NDR_RFLAG_DF                    (1 << 10)
-#define NDR_RFLAG_OF                    (1 << 11)
-#define NDR_RFLAG_IOPL                  (3 << 12)
-#define NDR_RFLAG_NT                    (1 << 14)
-#define NDR_RFLAG_RF                    (1 << 16)
-#define NDR_RFLAG_VM                    (1 << 17)
-#define NDR_RFLAG_AC                    (1 << 18)
-#define NDR_RFLAG_VIF                   (1 << 19)
-#define NDR_RFLAG_VIP                   (1 << 20)
-#define NDR_RFLAG_ID                    (1 << 21)
+#define NDR_RFLAG_CF                    (1ULL << 0)
+#define NDR_RFLAG_PF                    (1ULL << 2)
+#define NDR_RFLAG_AF                    (1ULL << 4)
+#define NDR_RFLAG_ZF                    (1ULL << 6)
+#define NDR_RFLAG_SF                    (1ULL << 7)
+#define NDR_RFLAG_TF                    (1ULL << 8)
+#define NDR_RFLAG_IF                    (1ULL << 9)
+#define NDR_RFLAG_DF                    (1ULL << 10)
+#define NDR_RFLAG_OF                    (1ULL << 11)
+#define NDR_RFLAG_IOPL                  (3ULL << 12)
+#define NDR_RFLAG_NT                    (1ULL << 14)
+#define NDR_RFLAG_RF                    (1ULL << 16)
+#define NDR_RFLAG_VM                    (1ULL << 17)
+#define NDR_RFLAG_AC                    (1ULL << 18)
+#define NDR_RFLAG_VIF                   (1ULL << 19)
+#define NDR_RFLAG_VIP                   (1ULL << 20)
+#define NDR_RFLAG_ID                    (1ULL << 21)
 
 #endif