diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2e3d601d..6c983c66 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -891,13 +891,6 @@ if(MSVC)
   string(REGEX REPLACE "/Z.[^:]" "/Z7 " CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG}")
   string(REGEX REPLACE "/Z.[^:]" "/Z7 " CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO}")
 
-  # Optimization flags. http://msdn.microsoft.com/en-us/magazine/cc301698.aspx
-  if(NOT ${CMAKE_BUILD_TYPE} MATCHES "Debug")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /GL")
-    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /LTCG")
-    set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} /LTCG")
-    set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} /LTCG")
-  endif()
 endif()
 
 # -----------------------------------------------------------------------------
@@ -1319,6 +1312,27 @@ if(MSVC)
                            VS_GLOBAL_RunCodeAnalysis true)
   endfunction()
   if(BUILD_SHARED)
+    # Whole Program Optimization flags. http://msdn.microsoft.com/en-us/magazine/cc301698.aspx
+    #
+    # "Finally, there's the subject of libraries. It's possible to create .LIB 
+    # files with code in its IL form. The linker will happily work with these 
+    # .LIB files. Be aware that these libraries will be tied to a specific 
+    # version of the compiler and linker. If you distribute these libraries, 
+    # you'll need to update them if Microsoft changes the format of IL in a 
+    # future release."
+    # 
+    # /GL and /LTCG can cause problems when libraries built with different 
+    # versions of compiler are later linked into an executable while /LTCG is active. 
+    # https://social.msdn.microsoft.com/Forums/vstudio/en-US/5c102025-c254-4f02-9a51-c775c6cc9f4b/problem-with-ltcg-when-building-a-static-library-in-vs2005?forum=vcgeneral
+    #
+    # For this reason, enable only when building a "Release" (e.g. non-DEBUG) DLL.
+    if(NOT ${CMAKE_BUILD_TYPE} MATCHES "Debug")
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /GL")
+      set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /LTCG")
+      set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} /LTCG")
+      set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} /LTCG")
+    endif()
+
     add_library(libzmq SHARED ${sources} ${public_headers} ${html-docs} ${readme-docs}
                               ${CMAKE_CURRENT_BINARY_DIR}/NSIS.template.in ${CMAKE_CURRENT_BINARY_DIR}/version.rc)
     if(ENABLE_ANALYSIS)