diff --git a/CMakeLists.txt b/CMakeLists.txt
index a4a433a5d..8375ea518 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,6 @@
 # SPDX-License-Identifier: Apache-2.0.
 
 cmake_minimum_required(VERSION 3.0)
-option(STATIC_CRT "Windows specific option that to specify static/dynamic run-time library" OFF)
 option(ALLOW_CROSS_COMPILED_TESTS "Allow tests to be compiled via cross compile, for use with qemu" OFF)
 
 project(aws-c-common LANGUAGES C VERSION 0.1.0)
diff --git a/cmake/AwsCFlags.cmake b/cmake/AwsCFlags.cmake
index fb4b14e1a..a4415c937 100644
--- a/cmake/AwsCFlags.cmake
+++ b/cmake/AwsCFlags.cmake
@@ -11,6 +11,7 @@ option(LEGACY_COMPILER_SUPPORT "This enables builds with compiler versions such
 option(AWS_SUPPORT_WIN7 "Restricts WINAPI calls to Win7 and older (This will have implications in downstream libraries that use TLS especially)" OFF)
 option(AWS_WARNINGS_ARE_ERRORS "Compiler warning is treated as an error. Try turning this off when observing errors on a new or uncommon compiler" OFF)
 option(AWS_ENABLE_TRACING "Enable tracing macros" OFF)
+option(STATIC_CRT "Windows-specific option to specify static/dynamic run-time library" OFF)
 
 # Check for Posix Large Files Support (LFS).
 # On most 64bit systems, LFS is enabled by default.
@@ -80,17 +81,17 @@ function(aws_set_common_properties target)
             list(APPEND AWS_C_FLAGS /DAWS_SUPPORT_WIN7=1)
         endif()
 
-        string(TOUPPER "${CMAKE_BUILD_TYPE}" _CMAKE_BUILD_TYPE)
-        if(STATIC_CRT)
-            string(REPLACE "/MD" "/MT" _FLAGS "${CMAKE_C_FLAGS_${_CMAKE_BUILD_TYPE}}")
+        # Set MSVC runtime libary.
+        # Note, there are better ways of doing this if we bump our CMake minimum to 3.14+
+        # See: https://cmake.org/cmake/help/latest/policy/CMP0091.html
+        if (STATIC_CRT)
+            list(APPEND AWS_C_FLAGS "/MT$<$<CONFIG:Debug>:d>")
         else()
-            string(REPLACE "/MT" "/MD" _FLAGS "${CMAKE_C_FLAGS_${_CMAKE_BUILD_TYPE}}")
+            list(APPEND AWS_C_FLAGS "/MD$<$<CONFIG:Debug>:d>")
         endif()
-        string(REPLACE " " ";" _FLAGS "${_FLAGS}")
-        list(APPEND AWS_C_FLAGS "${_FLAGS}")
 
     else()
-        list(APPEND AWS_C_FLAGS -Wall -Wstrict-prototypes)
+        lisD(APPEND AWS_C_FLAGS -Wall -Wstrict-prototypes)
 
         if (NOT CMAKE_BUILD_TYPE STREQUAL Release)
             list(APPEND AWS_C_FLAGS -fno-omit-frame-pointer)