diff --git a/src/configure.in b/src/configure.in
index b016fdc3d89..bc0020b1490 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -597,7 +597,7 @@ ice_save_CFLAGS="$CFLAGS"
 ice_save_CPPFLAGS="$CPPFLAGS"
 ice_save_LDFLAGS="$LDFLAGS"
 
-CPPFLAGS="$CPPFLAGS $X_CFLAGS -I$TCL_INCDIR"
+CPPFLAGS="$CPPFLAGS $X_CFLAGS"
 
 TK_INCDIR=no
 AC_CHECK_HEADER(tk.h, TK_INCDIR=)