diff --git a/CMakeLists.txt b/CMakeLists.txt
index fee56552..3eee0dae 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -28,7 +28,9 @@ set(CMAKE_CXX_EXTENSIONS OFF)
 if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
     add_compile_options("-Wall")
     add_compile_options("-Wextra")
+    add_compile_options("-Wconversion")
     add_compile_options("-pedantic")
+    
 endif()
 
 #---------------------------------------------------------------------------------------
diff --git a/bench/bench.cpp b/bench/bench.cpp
index f5a8060b..db14e1af 100644
--- a/bench/bench.cpp
+++ b/bench/bench.cpp
@@ -35,8 +35,8 @@ int main(int argc, char *argv[])
     int howmany = 1000000;
     int queue_size = howmany + 2;
     int threads = 10;
-    int file_size = 30 * 1024 * 1024;
-    int rotating_files = 5;
+    size_t file_size = 30 * 1024 * 1024;
+    size_t rotating_files = 5;
 
     try
     {
@@ -89,7 +89,7 @@ int main(int argc, char *argv[])
 
         for (int i = 0; i < 3; ++i)
         {
-            spdlog::init_thread_pool(queue_size, 1);
+            spdlog::init_thread_pool(static_cast<size_t>(queue_size), 1);
             auto as = spdlog::basic_logger_mt<spdlog::async_factory>("async", "logs/basic_async.log", true);
             bench_mt(howmany, as, threads);
             spdlog::drop("async");
diff --git a/bench/latency.cpp b/bench/latency.cpp
index 374eafb0..dcc6965c 100644
--- a/bench/latency.cpp
+++ b/bench/latency.cpp
@@ -35,8 +35,8 @@ int main(int, char *[])
     int howmany = 1000000;
     int queue_size = howmany + 2;
     int threads = 10;
-    int file_size = 30 * 1024 * 1024;
-    int rotating_files = 5;
+    size_t file_size = 30 * 1024 * 1024;
+    size_t rotating_files = 5;
 
     try
     {
@@ -82,7 +82,7 @@ int main(int, char *[])
 
         for (int i = 0; i < 3; ++i)
         {
-            spdlog::init_thread_pool(queue_size, 1);
+            spdlog::init_thread_pool(static_cast<size_t>(queue_size), 1);
             auto as = spdlog::basic_logger_mt<spdlog::async_factory>("async", "logs/basic_async.log", true);
             bench_mt(howmany, as, threads);
             spdlog::drop("async");
diff --git a/example/Makefile b/example/Makefile
index 01bdf507..bd6b2922 100644
--- a/example/Makefile
+++ b/example/Makefile
@@ -1,5 +1,5 @@
 CXX	?= g++
-CXX_FLAGS = -Wall -Wextra -pedantic -std=c++11 -pthread -I../include -fmax-errors=1
+CXX_FLAGS = -Wall -Wextra -pedantic -std=c++11 -pthread -I../include -fmax-errors=1 -Wconversion
 CXX_RELEASE_FLAGS = -O3 -march=native
 CXX_DEBUG_FLAGS= -g
 
diff --git a/include/spdlog/details/fmt_helper.h b/include/spdlog/details/fmt_helper.h
index eabf93b5..a94c7c5e 100644
--- a/include/spdlog/details/fmt_helper.h
+++ b/include/spdlog/details/fmt_helper.h
@@ -54,14 +54,14 @@ inline void pad2(int n, fmt::basic_memory_buffer<char, Buffer_Size> &dest)
     }
     if (n > 9) // 10-99
     {
-        dest.push_back('0' + static_cast<char>(n / 10));
-        dest.push_back('0' + static_cast<char>(n % 10));
+        dest.push_back(static_cast<char>('0' + n / 10));
+        dest.push_back(static_cast<char>('0' + n % 10));
         return;
     }
     if (n >= 0) // 0-9
     {
         dest.push_back('0');
-        dest.push_back('0' + static_cast<char>(n));
+        dest.push_back(static_cast<char>('0' + n));
         return;
     }
     // negatives (unlikely, but just in case, let fmt deal with it)
@@ -86,15 +86,15 @@ inline void pad3(int n, fmt::basic_memory_buffer<char, Buffer_Size> &dest)
     if (n > 9) // 10-99
     {
         dest.push_back('0');
-        dest.push_back('0' + static_cast<char>(n / 10));
-        dest.push_back('0' + static_cast<char>(n % 10));
+        dest.push_back(static_cast<char>('0' + n / 10));
+        dest.push_back(static_cast<char>('0' + n % 10));
         return;
     }
     if (n >= 0)
     {
         dest.push_back('0');
         dest.push_back('0');
-        dest.push_back('0' + static_cast<char>(n));
+        dest.push_back(static_cast<char>('0' + n));
         return;
     }
     // negatives (unlikely, but just in case let fmt deal with it)
diff --git a/include/spdlog/sinks/ostream_sink.h b/include/spdlog/sinks/ostream_sink.h
index 5f31993c..00c15959 100644
--- a/include/spdlog/sinks/ostream_sink.h
+++ b/include/spdlog/sinks/ostream_sink.h
@@ -30,7 +30,7 @@ protected:
     {
         fmt::memory_buffer formatted;
         sink::formatter_->format(msg, formatted);
-        ostream_.write(formatted.data(), formatted.size());
+        ostream_.write(formatted.data(), static_cast<std::streamsize>(formatted.size()));
         if (force_flush_)
             ostream_.flush();
     }
diff --git a/tests/Makefile b/tests/Makefile
index 00c7c589..bec3026d 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -1,5 +1,5 @@
 CXX	?= g++
-CXXFLAGS	=  -Wall  -pedantic -std=c++11 -pthread -O3 -I../include -fmax-errors=1
+CXXFLAGS	=  -Wall  -pedantic -std=c++11 -pthread -Wconversion -O3 -I../include -fmax-errors=1
 LDPFALGS = -pthread
 
 CPP_FILES := $(wildcard *.cpp)
diff --git a/tests/registry.cpp b/tests/registry.cpp
index 29bd1fc0..1b841a4c 100644
--- a/tests/registry.cpp
+++ b/tests/registry.cpp
@@ -9,7 +9,7 @@ TEST_CASE("register_drop", "[registry]")
     spdlog::create<spdlog::sinks::null_sink_mt>(tested_logger_name);
     REQUIRE(spdlog::get(tested_logger_name) != nullptr);
     // Throw if registring existing name
-    REQUIRE_THROWS_AS(spdlog::create<spdlog::sinks::null_sink_mt>(tested_logger_name), const spdlog::spdlog_ex&);
+    REQUIRE_THROWS_AS(spdlog::create<spdlog::sinks::null_sink_mt>(tested_logger_name), const spdlog::spdlog_ex &);
 }
 
 TEST_CASE("explicit register"
@@ -20,7 +20,7 @@ TEST_CASE("explicit register"
     spdlog::register_logger(logger);
     REQUIRE(spdlog::get(tested_logger_name) != nullptr);
     // Throw if registring existing name
-    REQUIRE_THROWS_AS(spdlog::create<spdlog::sinks::null_sink_mt>(tested_logger_name), const spdlog::spdlog_ex&);
+    REQUIRE_THROWS_AS(spdlog::create<spdlog::sinks::null_sink_mt>(tested_logger_name), const spdlog::spdlog_ex &);
 }
 
 TEST_CASE("apply_all"