diff --git a/src/build-defs.cmake b/src/build-defs.cmake
index f0b45b23103..7f3eb110766 100644
--- a/src/build-defs.cmake
+++ b/src/build-defs.cmake
@@ -7,7 +7,7 @@ if(UNIX)
   set(CMAKE_C_STANDARD 11)
   set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -L${PG_LIBDIR}")
   set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -L${PG_LIBDIR}")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${PG_CFLAGS} ${PG_CPPFLAGS}")
+  set(CMAKE_C_FLAGS "${PG_CFLAGS} ${PG_CPPFLAGS} ${CMAKE_C_FLAGS}")
   set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -g")
 endif()
 
diff --git a/tsl/src/build-defs.cmake b/tsl/src/build-defs.cmake
index 3ba9a42a4e1..0af17a4cc35 100644
--- a/tsl/src/build-defs.cmake
+++ b/tsl/src/build-defs.cmake
@@ -5,7 +5,7 @@ if(UNIX)
   set(CMAKE_C_STANDARD 11)
   set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -L${PG_LIBDIR}")
   set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -L${PG_LIBDIR}")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${PG_CFLAGS} ${PG_CPPFLAGS}")
+  set(CMAKE_C_FLAGS "${PG_CFLAGS} ${PG_CPPFLAGS} ${CMAKE_C_FLAGS}")
   set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -g")
 endif()