diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1b77c1b..a7935d5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -54,12 +54,8 @@ if (MSVC)
         /EHsc
         /Zc:throwingNew # Assumes new never returns null
         /Zc:inline # Omits inline functions from object-file output
-        /DNOMINMAX)
-
-    if (SIRIT_WARNINGS_AS_ERRORS)
-        list(APPEND SIRIT_CXX_FLAGS
-             /WX)
-    endif()
+        /DNOMINMAX
+        /WX)
 
     if (CMAKE_VS_PLATFORM_TOOLSET MATCHES "LLVM-vs[0-9]+")
         list(APPEND SIRIT_CXX_FLAGS
@@ -74,12 +70,10 @@ else()
         -pedantic
         -pedantic-errors
         -Wfatal-errors
-        -Wno-missing-braces)
-
-    if (SIRIT_WARNINGS_AS_ERRORS)
-        list(APPEND SIRIT_CXX_FLAGS
-             -Werror)
-    endif()
+        -Wno-missing-braces
+        -Wconversion
+        -Wsign-conversion
+        -Werror)
 endif()
 
 # Enable unit-testing.
diff --git a/src/literal_number.cpp b/src/literal_number.cpp
index 4fafb9e..f418be4 100644
--- a/src/literal_number.cpp
+++ b/src/literal_number.cpp
@@ -22,7 +22,7 @@ void LiteralNumber::Fetch(Stream& stream) const {
     }
 }
 
-u16 LiteralNumber::GetWordCount() const noexcept {
+std::size_t LiteralNumber::GetWordCount() const noexcept {
     return is_32 ? 1 : 2;
 }
 
diff --git a/src/literal_number.h b/src/literal_number.h
index fda0226..6fd60d1 100644
--- a/src/literal_number.h
+++ b/src/literal_number.h
@@ -6,8 +6,10 @@
 
 #pragma once
 
+#include <cstddef>
 #include <cstring>
 #include <memory>
+
 #include "operand.h"
 #include "stream.h"
 
@@ -20,7 +22,7 @@ public:
 
     void Fetch(Stream& stream) const override;
 
-    u16 GetWordCount() const noexcept override;
+    std::size_t GetWordCount() const noexcept override;
 
     bool operator==(const Operand& other) const noexcept override;
 
diff --git a/src/literal_string.cpp b/src/literal_string.cpp
index 9b8f062..bc8e6e1 100644
--- a/src/literal_string.cpp
+++ b/src/literal_string.cpp
@@ -19,8 +19,8 @@ void LiteralString::Fetch(Stream& stream) const {
     stream.Write(string);
 }
 
-u16 LiteralString::GetWordCount() const noexcept {
-    return static_cast<u16>(string.size() / 4 + 1);
+std::size_t LiteralString::GetWordCount() const noexcept {
+    return string.size() / 4 + 1;
 }
 
 bool LiteralString::operator==(const Operand& other) const noexcept {
diff --git a/src/literal_string.h b/src/literal_string.h
index 4cf5287..7c051d1 100644
--- a/src/literal_string.h
+++ b/src/literal_string.h
@@ -19,7 +19,7 @@ public:
 
     void Fetch(Stream& stream) const override;
 
-    u16 GetWordCount() const noexcept override;
+    std::size_t GetWordCount() const noexcept override;
 
     bool operator==(const Operand& other) const noexcept override;
 
diff --git a/src/op.cpp b/src/op.cpp
index f5b9b75..6319584 100644
--- a/src/op.cpp
+++ b/src/op.cpp
@@ -6,6 +6,7 @@
 
 #include <algorithm>
 #include <cassert>
+#include <limits>
 
 #include "common_types.h"
 #include "literal_number.h"
@@ -25,7 +26,7 @@ void Op::Fetch(Stream& stream) const {
     stream.Write(id.value());
 }
 
-u16 Op::GetWordCount() const noexcept {
+std::size_t Op::GetWordCount() const noexcept {
     return 1;
 }
 
@@ -47,7 +48,7 @@ bool Op::operator==(const Operand& other) const noexcept {
 }
 
 void Op::Write(Stream& stream) const {
-    stream.Write(static_cast<u16>(opcode), WordCount());
+    stream.Write(static_cast<u16>(opcode), CalculateTotalWords());
 
     if (result_type) {
         result_type->Fetch(stream);
@@ -99,7 +100,11 @@ void Op::Add(const Operand* operand) {
 }
 
 void Op::Add(u32 integer) {
-    Sink(LiteralNumber::Create<u32>(integer));
+    Sink(LiteralNumber::Create(integer));
+}
+
+void Op::Add(s32 integer) {
+    Sink(LiteralNumber::Create(integer));
 }
 
 void Op::Add(std::string string) {
@@ -111,18 +116,19 @@ void Op::Add(const std::vector<Id>& ids) {
     operands.insert(operands.end(), ids.begin(), ids.end());
 }
 
-u16 Op::WordCount() const {
-    u16 count = 1;
+u16 Op::CalculateTotalWords() const noexcept {
+    std::size_t count = 1;
     if (result_type) {
-        count++;
+        ++count;
     }
     if (id.has_value()) {
-        count++;
+        ++count;
     }
     for (const Operand* operand : operands) {
         count += operand->GetWordCount();
     }
-    return count;
+    assert(count < std::numeric_limits<u16>::max());
+    return static_cast<u16>(count);
 }
 
 } // namespace Sirit
diff --git a/src/op.h b/src/op.h
index a7413f8..cc16ac3 100644
--- a/src/op.h
+++ b/src/op.h
@@ -6,7 +6,10 @@
 
 #pragma once
 
+#include <cstddef>
 #include <optional>
+#include <vector>
+
 #include "common_types.h"
 #include "operand.h"
 #include "sirit/sirit.h"
@@ -21,7 +24,7 @@ public:
 
     void Fetch(Stream& stream) const override;
 
-    u16 GetWordCount() const noexcept override;
+    std::size_t GetWordCount() const noexcept override;
 
     bool operator==(const Operand& other) const noexcept override;
 
@@ -37,12 +40,14 @@ public:
 
     void Add(u32 integer);
 
+    void Add(s32 integer);
+
     void Add(std::string string);
 
     void Add(const std::vector<Id>& ids);
 
 private:
-    u16 WordCount() const;
+    u16 CalculateTotalWords() const noexcept;
 
     spv::Op opcode;
 
diff --git a/src/operand.h b/src/operand.h
index 64e951b..4e19f80 100644
--- a/src/operand.h
+++ b/src/operand.h
@@ -6,6 +6,8 @@
 
 #pragma once
 
+#include <cstddef>
+
 #include "stream.h"
 
 namespace Sirit {
@@ -19,7 +21,7 @@ public:
 
     virtual void Fetch(Stream& stream) const = 0;
 
-    virtual u16 GetWordCount() const noexcept = 0;
+    virtual std::size_t GetWordCount() const noexcept = 0;
 
     virtual bool operator==(const Operand& other) const noexcept = 0;
 
diff --git a/src/stream.cpp b/src/stream.cpp
index 2282364..7a60faf 100644
--- a/src/stream.cpp
+++ b/src/stream.cpp
@@ -15,7 +15,9 @@ Stream::~Stream() = default;
 void Stream::Write(std::string_view string) {
     constexpr std::size_t word_size = 4;
     const auto size = string.size();
-    auto read = [string, size](std::size_t offset) { return offset < size ? string[offset] : 0; };
+    const auto read = [string, size](std::size_t offset) {
+        return offset < size ? static_cast<u8>(string[offset]) : u8(0);
+    };
 
     words.reserve(words.size() + size / word_size + 1);
     for (std::size_t i = 0; i < size; i += word_size) {