diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc
index d49e5a565e823aba7a23fcf746e037408379dbb3..3b8dc75d1986f9e7b708766a07051aa8b003a708 100644
--- a/gcc/cp/method.cc
+++ b/gcc/cp/method.cc
@@ -1228,7 +1228,11 @@ early_check_defaulted_comparison (tree fn)
 	  /* Defaulted outside the class body.  */
 	  ctx = TYPE_MAIN_VARIANT (parmtype);
 	  if (!is_friend (ctx, fn))
-	    error_at (loc, "defaulted %qD is not a friend of %qT", fn, ctx);
+	    {
+	      error_at (loc, "defaulted %qD is not a friend of %qT", fn, ctx);
+	      inform (location_of (ctx), "declared here");
+	      ok = false;
+	    }
 	}
       else if (!same_type_ignoring_top_level_qualifiers_p (parmtype, ctx))
 	saw_bad = true;
diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-eq17.C b/gcc/testsuite/g++.dg/cpp2a/spaceship-eq17.C
new file mode 100644
index 0000000000000000000000000000000000000000..039bfac387c3cb71b81b33b6cab8b76791cff8b5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-eq17.C
@@ -0,0 +1,5 @@
+// PR c++/107291
+// { dg-do compile { target c++20 } }
+
+struct S4;					   // { dg-message "declared here" }
+bool operator==(S4 const &, S4 const &) = default; // { dg-error "not a friend" }