diff --git a/cpp/BoostParts/CMakeLists.txt b/cpp/BoostParts/CMakeLists.txt
index 14e37a4e..6b0d3675 100644
--- a/cpp/BoostParts/CMakeLists.txt
+++ b/cpp/BoostParts/CMakeLists.txt
@@ -118,3 +118,8 @@ if( MSVC )
     set( CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} /Oi /GL" )
     set_target_properties( ${PROJECT_NAME} PROPERTIES STATIC_LIBRARY_FLAGS "/LTCG" )
 endif()
+
+if( SYSTEM_IS_SUNOS )
+  # SunOS needs this setting for thread support
+  set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthreads" )
+endif()
diff --git a/cpp/CMakeLists.txt b/cpp/CMakeLists.txt
index 7afe590b..fecda10b 100644
--- a/cpp/CMakeLists.txt
+++ b/cpp/CMakeLists.txt
@@ -28,6 +28,10 @@ if ( ${CMAKE_SYSTEM_NAME} MATCHES "FreeBSD" )
   set( SYSTEM_IS_FREEBSD true )
 endif()
 
+if ( ${CMAKE_SYSTEM_NAME} MATCHES "SunOS" )
+  set( SYSTEM_IS_SUNOS true )
+endif()
+
 # Check if platform is 64 bit
 if( CMAKE_SIZEOF_VOID_P EQUAL 4 )
   set( 64_BIT_PLATFORM 0 )
diff --git a/cpp/ycm/CMakeLists.txt b/cpp/ycm/CMakeLists.txt
index 52e7afd6..44ea8717 100644
--- a/cpp/ycm/CMakeLists.txt
+++ b/cpp/ycm/CMakeLists.txt
@@ -313,4 +313,9 @@ endif()
 
 #############################################################################
 
+if( SYSTEM_IS_SUNOS )
+  # SunOS needs this setting for thread support
+  set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthreads" )
+endif()
+
 add_subdirectory( tests )