diff --git a/Makefile b/Makefile
index ffa1107..6d981a4 100644
--- a/Makefile
+++ b/Makefile
@@ -86,13 +86,13 @@ interpret: $(VM_OUT)
 .PHONY: run-test-lib
 .ONESHELL:
 run-test-lib: $(TEST_LIB_OUT)
-	@echo "$(TERM_YELLOW)test/lib$(TERM_RESET): Starting test"
+	@echo "$(TERM_YELLOW)test/lib$(TERM_RESET): Starting tests"
 	@./$^;
 	if [ $$? -ne 0 ];
 	then
-		echo "$(TERM_RED)test/lib$(TERM_RESET): Test failed";
+		echo "$(TERM_RED)test/lib$(TERM_RESET): Tests failed";
 	else
-		echo "$(TERM_GREEN)test/lib$(TERM_RESET): Test passed";
+		echo "$(TERM_GREEN)test/lib$(TERM_RESET): Tests passed";
 	fi
 
 # Directories
diff --git a/lib/inst-macro.h b/lib/inst-macro.h
index b45cc5a..3aac840 100644
--- a/lib/inst-macro.h
+++ b/lib/inst-macro.h
@@ -22,7 +22,7 @@
   ((inst_t){.opcode = OP_PUSH_##TYPE, .operand = D##TYPE(OP)})
 
 #define INST_MOV(TYPE, OP) \
-  ((inst_t){.opcode = OP_MOV_##TYPE, .operand = D##TYPE(OP)})
+  ((inst_t){.opcode = OP_MOV_##TYPE, .operand = DWORD(OP)})
 
 #define INST_POP(TYPE) ((inst_t){.opcode = OP_POP_##TYPE})
 
diff --git a/lib/inst.c b/lib/inst.c
index b41029a..3c1eb4a 100644
--- a/lib/inst.c
+++ b/lib/inst.c
@@ -245,7 +245,7 @@ void data_print(data_t datum, data_type_t type, FILE *fp)
 
 void inst_print(inst_t instruction, FILE *fp)
 {
-  static_assert(NUMBER_OF_OPCODES == 98, "inst_print: Out of date");
+  static_assert(NUMBER_OF_OPCODES == 99, "inst_print: Out of date");
   fprintf(fp, "%s(", opcode_as_cstr(instruction.opcode));
   if (UNSIGNED_OPCODE_IS_TYPE(instruction.opcode, OP_PUSH))
   {
@@ -264,7 +264,7 @@ void inst_print(inst_t instruction, FILE *fp)
            UNSIGNED_OPCODE_IS_TYPE(instruction.opcode, OP_MSET) ||
            UNSIGNED_OPCODE_IS_TYPE(instruction.opcode, OP_MGET))
   {
-    fprintf(fp, "n=%lu", instruction.operand.as_word);
+    fprintf(fp, "n=0x%lX", instruction.operand.as_word);
   }
   else if (instruction.opcode == OP_JUMP_ABS ||
            UNSIGNED_OPCODE_IS_TYPE(instruction.opcode, OP_JUMP_IF) ||
@@ -278,7 +278,7 @@ void inst_print(inst_t instruction, FILE *fp)
 
 size_t opcode_bytecode_size(opcode_t opcode)
 {
-  static_assert(NUMBER_OF_OPCODES == 98, "inst_bytecode_size: Out of date");
+  static_assert(NUMBER_OF_OPCODES == 99, "inst_bytecode_size: Out of date");
   size_t size = 1; // for opcode
   if (UNSIGNED_OPCODE_IS_TYPE(opcode, OP_PUSH))
   {
@@ -303,15 +303,16 @@ size_t opcode_bytecode_size(opcode_t opcode)
 
 size_t inst_write_bytecode(inst_t inst, byte_t *bytes)
 {
-  static_assert(NUMBER_OF_OPCODES == 98, "inst_write_bytecode: Out of date");
+  static_assert(NUMBER_OF_OPCODES == 99, "inst_write_bytecode: Out of date");
 
-  size_t written = 1;
   bytes[0]       = inst.opcode;
+  size_t written = 1;
   // Then append 0 or more operands
   data_type_t to_append = DATA_TYPE_NIL;
   if (UNSIGNED_OPCODE_IS_TYPE(inst.opcode, OP_PUSH))
-    to_append = (data_type_t)inst.opcode;
+    to_append = OPCODE_DATA_TYPE(inst.opcode, OP_PUSH);
   else if (UNSIGNED_OPCODE_IS_TYPE(inst.opcode, OP_PUSH_REGISTER) ||
+           UNSIGNED_OPCODE_IS_TYPE(inst.opcode, OP_DUP) ||
            UNSIGNED_OPCODE_IS_TYPE(inst.opcode, OP_MOV) ||
            UNSIGNED_OPCODE_IS_TYPE(inst.opcode, OP_DUP) ||
            UNSIGNED_OPCODE_IS_TYPE(inst.opcode, OP_MALLOC) ||
@@ -325,19 +326,22 @@ size_t inst_write_bytecode(inst_t inst, byte_t *bytes)
   {
   case DATA_TYPE_NIL:
     break;
-  case DATA_TYPE_BYTE:
+  case DATA_TYPE_BYTE: {
     bytes[1] = inst.operand.as_byte;
     written += 1;
     break;
-  case DATA_TYPE_HWORD:
+  }
+  case DATA_TYPE_HWORD: {
     convert_hword_to_bytes(inst.operand.as_hword, bytes + 1);
     written += HWORD_SIZE;
     break;
-  case DATA_TYPE_WORD:
+  }
+  case DATA_TYPE_WORD: {
     convert_word_to_bytes(inst.operand.as_word, bytes + 1);
     written += WORD_SIZE;
     break;
   }
+  }
   return written;
 }
 
@@ -375,10 +379,10 @@ bool read_type_from_darr(byte_t *bytes, size_t size, data_type_t type,
 
 int inst_read_bytecode(inst_t *ptr, byte_t *bytes, size_t size_bytes)
 {
-  static_assert(NUMBER_OF_OPCODES == 98, "inst_read_bytecode: Out of date");
+  static_assert(NUMBER_OF_OPCODES == 99, "inst_read_bytecode: Out of date");
 
   opcode_t opcode = *(bytes++);
-  if (opcode > OP_HALT || opcode == NUMBER_OF_OPCODES || opcode < OP_NOOP)
+  if (opcode > OP_HALT || opcode < OP_NOOP)
     return READ_ERR_INVALID_OPCODE;
 
   inst_t inst = {opcode, {0}};
@@ -409,7 +413,7 @@ int inst_read_bytecode(inst_t *ptr, byte_t *bytes, size_t size_bytes)
   if (success)
   {
     *ptr = inst;
-    return (int)(READ_ERR_END) - (int)(size_bytes);
+    return (int)(size_bytes);
   }
   else
     return READ_ERR_OPERAND_NO_FIT;
diff --git a/lib/inst.h b/lib/inst.h
index 3daf50f..6f14830 100644
--- a/lib/inst.h
+++ b/lib/inst.h
@@ -161,9 +161,9 @@ typedef enum
   OP_CALL_STACK,
   OP_RET,
 
+  OP_HALT,
   // Should not be an opcode
   NUMBER_OF_OPCODES,
-  OP_HALT = 0b11111111, // top of the byte is a HALT
 } opcode_t;
 
 size_t opcode_bytecode_size(opcode_t);
diff --git a/test/testing.h b/test/testing.h
index 057b25a..afd5b0a 100644
--- a/test/testing.h
+++ b/test/testing.h
@@ -50,15 +50,15 @@ struct Test
   for (size_t i = 0; i < ARR_SIZE(SUITE); ++i)            \
   {                                                       \
     SUITE[i].src();                                       \
-    SUCCESS(SUITE[i].name, "%s\n", "Test succeeded");     \
+    SUCCESS(SUITE[i].name, "%s\n", "Test passed");        \
   }                                                       \
-  SUCCESS("<" #SUITE ">", "%s", "Finished test suite!\n")
+  SUCCESS("<" #SUITE ">", "%s", "Test suite passed!\n")
 #else
 #define RUN_TEST_SUITE(SUITE)                             \
   INFO("<" #SUITE ">", "%s", "Starting test suite...\n"); \
   for (size_t i = 0; i < ARR_SIZE(SUITE); ++i)            \
     SUITE[i].src();                                       \
-  SUCCESS("<" #SUITE ">", "%s", "Finished test suite!\n")
+  SUCCESS("<" #SUITE ">", "%s", "Test suite passed!\n")
 #endif
 
 static size_t size_byte_array_to_string(const size_t n)
@@ -73,12 +73,11 @@ static void byte_array_to_string(const byte_t *bytes, size_t size_bytes,
   size_t j = 1;
   for (size_t i = 0; i < size_bytes; ++i)
   {
-    ;
     char buffer[7];
     int k    = i == size_bytes - 1 ? 0 : 2;
-    size_t n = 2 + (bytes[i] < 10 ? 1 : 2) + k;
+    size_t n = 4 + k;
 
-    sprintf(buffer, "0x%X, ", bytes[i]);
+    sprintf(buffer, "0x%s%X, ", (bytes[i] < 16 ? "_" : ""), bytes[i]);
     memcpy(str + j, buffer, n);
     j += n;
   }
diff --git a/vm/runtime.c b/vm/runtime.c
index aea8013..1e0f20a 100644
--- a/vm/runtime.c
+++ b/vm/runtime.c
@@ -54,7 +54,7 @@ const char *err_as_cstr(err_t err)
   }
 }
 
-static_assert(NUMBER_OF_OPCODES == 98, "vm_execute: Out of date");
+static_assert(NUMBER_OF_OPCODES == 99, "vm_execute: Out of date");
 
 static_assert(DATA_TYPE_NIL == -1 && DATA_TYPE_WORD == 2,
               "Code using OPCODE_DATA_TYPE for quick same type opcode "