diff --git a/gcc/gimple.h b/gcc/gimple.h
index 6b1e89ad74e..870629cd562 100644
--- a/gcc/gimple.h
+++ b/gcc/gimple.h
@@ -1913,7 +1913,8 @@ static inline void
 gimple_set_location (gimple *g, location_t location)
 {
   /* Copy the no-warning data to the statement location.  */
-  copy_warning (location, g->location);
+  if (g->location != UNKNOWN_LOCATION)
+    copy_warning (location, g->location);
   g->location = location;
 }
 
diff --git a/gcc/testsuite/c-c++-common/nonnull-1.c b/gcc/testsuite/c-c++-common/nonnull-1.c
index ea987365302..7be4e3479dd 100644
--- a/gcc/testsuite/c-c++-common/nonnull-1.c
+++ b/gcc/testsuite/c-c++-common/nonnull-1.c
@@ -30,5 +30,5 @@ func (char *cp1, char *cp2, char *cp3, char *cp4)
 __attribute__((nonnull (1))) int
 func2 (char *cp)
 {
-  return (cp != NULL) ? 1 : 0; /* { dg-warning "'nonnull' argument" "cp compared to NULL" { xfail c++ } } */
+  return (cp != NULL) ? 1 : 0; /* { dg-warning "'nonnull' argument" "cp compared to NULL" } */
 }