diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index bbb2a61ae35..aff9383d936 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -2706,27 +2706,21 @@ operator_logical_not::fold_range (irange &r, tree type,
   if (empty_range_varying (r, type, lh, rh))
     return true;
 
-  if (lh.varying_p () || lh.undefined_p ())
-    r = lh;
-  else
-    {
-      r = lh;
-      r.invert ();
-    }
-  gcc_checking_assert (lh.type() == type);
+  r = lh;
+  if (!lh.varying_p () && !lh.undefined_p ())
+    r.invert ();
+
   return true;
 }
 
 bool
 operator_logical_not::op1_range (irange &r,
-				 tree type ATTRIBUTE_UNUSED,
+				 tree type,
 				 const irange &lhs,
-				 const irange &op2 ATTRIBUTE_UNUSED) const
+				 const irange &op2) const
 {
-  r = lhs;
-  if (!lhs.varying_p () && !lhs.undefined_p ())
-    r.invert ();
-  return true;
+  // Logical NOT is involutary...do it again.
+  return fold_range (r, type, lhs, op2);
 }
 
 
@@ -2749,6 +2743,9 @@ operator_bitwise_not::fold_range (irange &r, tree type,
   if (empty_range_varying (r, type, lh, rh))
     return true;
 
+  if (types_compatible_p (type, boolean_type_node))
+    return op_logical_not.fold_range (r, type, lh, rh);
+
   // ~X is simply -1 - X.
   int_range<1> minusone (type, wi::minus_one (TYPE_PRECISION (type)),
 			 wi::minus_one (TYPE_PRECISION (type)));
@@ -2761,6 +2758,9 @@ operator_bitwise_not::op1_range (irange &r, tree type,
 				 const irange &lhs,
 				 const irange &op2) const
 {
+  if (types_compatible_p (type, boolean_type_node))
+    return op_logical_not.op1_range (r, type, lhs, op2);
+
   // ~X is -1 - X and since bitwise NOT is involutary...do it again.
   return fold_range (r, type, lhs, op2);
 }
diff --git a/gcc/testsuite/gnat.dg/opt88.adb b/gcc/testsuite/gnat.dg/opt88.adb
new file mode 100644
index 00000000000..a6abd018611
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt88.adb
@@ -0,0 +1,52 @@
+-- { dg-do run }
+-- { dg-options "-O -ftree-vrp -fno-inline" }
+
+procedure Opt88 is
+
+  Val : Integer := 1;
+
+  procedure Dummy (B : out Boolean) is
+  begin
+    B := True;
+  end;
+
+  function Test return Boolean is
+  begin
+    return False;
+  end;
+
+  procedure Do_It (OK : out Boolean) is
+
+    Blue : Boolean := False;
+    Red  : Boolean := False;
+
+  begin
+    OK := True;
+    Blue := True;
+    Dummy (Red);
+
+    if Red then
+      Red := False;
+
+      if Test then
+        Dummy (Red);
+      end if;
+    end if;
+
+    if Blue and not Red then
+      Val := 0;
+    end if;
+
+    if Red then
+      OK := False;
+    end if;
+  end;
+
+  OK : Boolean;
+
+begin
+  Do_It (OK);
+  if not OK then
+    raise Program_Error;
+  end if;
+end;