diff --git a/include/llvm/Support/DataTypes.h.in b/include/llvm/Support/DataTypes.h.in
index c218193b932..6b3aee8ce62 100644
--- a/include/llvm/Support/DataTypes.h.in
+++ b/include/llvm/Support/DataTypes.h.in
@@ -36,12 +36,15 @@
 @INCLUDE_INTTYPES_H@
 @INCLUDE_SYS_TYPES_H@
 @INCLUDE_STDINT_H@
-// Interix has u_int64_t, but not uint64_t
-#if !defined(HAVE_UINT64_T) && defined(HAVE_U_INT64_T)
+
+// Handle incorrect definition of uint64_t as u_int64_t
+#ifndef HAVE_UINT64_T
+#ifdef HAVE_U_INT64_T
 typedef u_int64_t uint64_t;
 #else
 # error "Don't have a definition for uint64_t on this platform"
 #endif
+#endif
 
 #else
 // Visual C++ doesn't provide standard integer headers, but it does provide