diff --git a/Source/CTest/Curl/CMake/CurlTests.c b/Source/CTest/Curl/CMake/CurlTests.c
index 52547166d..fba8dc42d 100644
--- a/Source/CTest/Curl/CMake/CurlTests.c
+++ b/Source/CTest/Curl/CMake/CurlTests.c
@@ -412,8 +412,10 @@ int main(void) {
     return 0;
 }
 #endif
+#ifdef HAVE_FILE_OFFSET_BITS
 #ifdef _FILE_OFFSET_BITS
 #undef _FILE_OFFSET_BITS
+#endif
 #define _FILE_OFFSET_BITS 64
 #include <sys/types.h>
  /* Check that off_t can represent 2**63 - 1 correctly.
diff --git a/Source/CTest/Curl/CMakeLists.txt b/Source/CTest/Curl/CMakeLists.txt
index deadb9609..3d2880c29 100644
--- a/Source/CTest/Curl/CMakeLists.txt
+++ b/Source/CTest/Curl/CMakeLists.txt
@@ -400,10 +400,13 @@ FOREACH(CURL_TEST
     HAVE_INET_NTOA_R_DECL
     HAVE_INET_NTOA_R_DECL_REENTRANT
     HAVE_GETADDRINFO
-    _FILE_OFFSET_BITS
+    HAVE_FILE_OFFSET_BITS
     )
   CURL_INTERNAL_TEST(${CURL_TEST})
 ENDFOREACH(CURL_TEST)
+IF(HAVE_FILE_OFFSET_BITS)
+  SET(_FILE_OFFSET_BITS 64)
+ENDIF(HAVE_FILE_OFFSET_BITS)
 
 # Check for reentrant
 FOREACH(CURL_TEST