diff --git a/configure.in b/configure.in
index e1fd88f4536d482ec429cd50f004752cbe09acef..85ad7fd8fef5c2b4b9e12e95a286ebe83f78cf98 100644
--- a/configure.in
+++ b/configure.in
@@ -416,6 +416,8 @@ if test "$OCAML_OS_TYPE" = "Win32"; then
 else
   OCAMLWIN32=no
   if test "$OCAML_OS_TYPE" = "Cygwin"; then
+    AC_MSG_WARN([Compilation using Cygwin is unsupported;
+                 consider using a MinGW-based compiler.])
     AC_MSG_RESULT(Cygwin)
     PLATFORM=Cygwin
     EXE=.exe