diff --git a/3rd/math/src/fsum.c b/3rd/math/src/fsum.c
index 88ef2b3e..3bb83a91 100644
--- a/3rd/math/src/fsum.c
+++ b/3rd/math/src/fsum.c
@@ -10,7 +10,7 @@ double fsum(double* aptr, int n)
 		Y = aptr[i] - C;
 		T = sum + Y;
 		C = T - sum - Y;
-		sum = Y;
+		sum = T;
 	}
 	return sum;
 }
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3f7351d1..105dde48 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -50,6 +50,13 @@ if(PK_ENABLE_DETERMINISTIC_FLOAT)
     add_subdirectory(3rd/math)
     include_directories(3rd/math)
     add_definitions(-DPK_ENABLE_DETERMINISTIC_FLOAT)
+    if(MSVC)
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /fp:precise")
+    elseif(CMAKE_C_COMPILER_ID STREQUAL "Clang")
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -ffp-model=strict -O2")
+    else()
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2")
+    endif()
 endif()
 
 option(PK_BUILD_MODULE_LZ4 "" OFF)
@@ -114,6 +121,9 @@ if(PK_BUILD_WITH_UNITY)
 endif()
 
 ############################################
+if(NOT MSVC)
+    target_link_libraries(${PROJECT_NAME} pthread)
+endif()
 if(PK_BUILD_MODULE_LZ4)
     target_link_libraries(${PROJECT_NAME} lz4)
 endif()