diff --git a/src/db/db/gsiDeclDbTrans.cc b/src/db/db/gsiDeclDbTrans.cc
index 794e787b5..eea902139 100644
--- a/src/db/db/gsiDeclDbTrans.cc
+++ b/src/db/db/gsiDeclDbTrans.cc
@@ -33,6 +33,43 @@
 namespace gsi
 {
 
+// ---------------------------------------------------------------
+//  A helper for the single-coordinate/distance transformation
+
+namespace
+{
+
+template <class C> struct long_coord;
+
+template<> struct long_coord<int32_t>
+{
+  typedef int64_t type;
+  static type rounded (double v)
+  {
+    return type (v > 0 ? v + 0.5 : v - 0.5);
+  }
+};
+
+template<> struct long_coord<int64_t>
+{
+  typedef int64_t type;
+  static type rounded (double v)
+  {
+    return type (v > 0 ? v + 0.5 : v - 0.5);
+  }
+};
+
+template<> struct long_coord<double>
+{
+  typedef double type;
+  static type rounded (double v)
+  {
+    return v;
+  }
+};
+
+}
+
 // ---------------------------------------------------------------
 //  simple_trans binding
 
@@ -111,6 +148,11 @@ struct trans_defs
     *trans = C (trans->angle (), mirror, trans->disp ());
   }
 
+  static typename long_coord<coord_type>::type trans_coord (const C * /*t*/, typename long_coord<coord_type>::type c)
+  {
+    return long_coord<coord_type>::rounded (double (c));
+  }
+
   static db::edge<coord_type> trans_edge (const C *t, const db::edge<coord_type> &edge)
   {
     return edge.transformed (*t);
@@ -219,18 +261,18 @@ struct trans_defs
       "\n"
       "@return The inverted transformation\n"
     ) +
-    method ("ctrans|*", &C::ctrans, arg ("d"),
-      "@brief Transforms a distance\n"
+    method_ext ("ctrans|*", &trans_coord, arg ("d"),
+      "@brief Transforms a single distance\n"
       "\n"
       "The \"ctrans\" method transforms the given distance.\n"
-      "e = t(d). For the simple transformations, there\n"
-      "is no magnification and no modification of the distance\n"
-      "therefore.\n"
+      "This is equivalent to multiplying with the magnification. For the simple transformations, there\n"
+      "is no magnification and no modification of the distance.\n"
       "\n"
       "@param d The distance to transform\n"
       "@return The transformed distance\n"
       "\n"
-      "The product '*' has been added as a synonym in version 0.28."
+      "The product '*' has been added as a synonym in version 0.28. "
+      "The distance can be signed since version 0.29.3."
     ) +
     method ("trans|*", (point_type (C::*) (const point_type &) const) &C::trans, arg ("p"),
       "@brief Transforms a point\n"
@@ -604,6 +646,11 @@ struct cplx_trans_defs
     return new C (mag, r, mirrx, displacement_type (x, y));
   }
 
+  static typename long_coord<target_coord_type>::type trans_coord (const C *t, typename long_coord<coord_type>::type c)
+  {
+    return long_coord<target_coord_type>::rounded (t->mag () * double (c));
+  }
+
   static simple_trans_type s_trans (const C *cplx_trans)
   {
     return simple_trans_type (db::complex_trans<coord_type, coord_type> (*cplx_trans));
@@ -729,18 +776,18 @@ struct cplx_trans_defs
       "\n"
       "@return The inverted transformation\n"
     ) +
-    method ("ctrans|*", &C::ctrans, arg ("d"),
-      "@brief Transforms a distance\n"
+    method_ext ("ctrans|*", &trans_coord, arg ("d"),
+      "@brief Transforms a single distance\n"
       "\n"
       "The \"ctrans\" method transforms the given distance.\n"
-      "e = t(d). For the simple transformations, there\n"
-      "is no magnification and no modification of the distance\n"
-      "therefore.\n"
+      "This is equivalent to multiplying with the magnification. For the simple transformations, there\n"
+      "is no magnification and no modification of the distance.\n"
       "\n"
       "@param d The distance to transform\n"
       "@return The transformed distance\n"
       "\n"
-      "The product '*' has been added as a synonym in version 0.28."
+      "The product '*' has been added as a synonym in version 0.28. "
+      "The distance can be signed since version 0.29.3."
     ) +
     method ("trans|*", (target_point_type (C::*) (const point_type &) const) &C::trans, arg ("p"),
       "@brief Transforms a point\n"
diff --git a/testdata/ruby/dbTransTest.rb b/testdata/ruby/dbTransTest.rb
index b5d6f3444..9d669e4b0 100644
--- a/testdata/ruby/dbTransTest.rb
+++ b/testdata/ruby/dbTransTest.rb
@@ -81,7 +81,9 @@ class DBTrans_TestClass < TestBase
     assert_equal( RBA::Trans::new(RBA::Trans::R180).to_s, "r180 0,0" )
 
     assert_equal( e.ctrans( 2.0 ), 2.0 )
+    assert_equal( e.ctrans( -2.0 ), -2.0 )
     assert_equal( e * 2.0, 2.0 )
+    assert_equal( e * -2.0, -2.0 )
     assert_equal( e.trans( RBA::Edge::new(0, 1, 2, 3) ).to_s, "(-3,-2;-1,0)" )
     assert_equal( ( e * RBA::Edge::new(0, 1, 2, 3) ).to_s, "(-3,-2;-1,0)" )
     assert_equal( e.trans( RBA::Box::new(0, 1, 2, 3) ).to_s, "(-3,-2;-1,0)" )
@@ -142,9 +144,13 @@ class DBTrans_TestClass < TestBase
 
     assert_equal( mb.trans( RBA::DPoint::new( 1, 0 )).to_s, "17,3" )
     assert_equal( mb.ctrans(2).to_s, "4.0" )
+    assert_equal( mb.ctrans(-2).to_s, "-4.0" )
     assert_equal( (mb * 2).to_s, "4.0" )
+    assert_equal( (mb * -2).to_s, "-4.0" )
     assert_equal( i.ctrans(2).to_s, "1.0" )
+    assert_equal( i.ctrans(-2).to_s, "-1.0" )
     assert_equal( (i * 2).to_s, "1.0" )
+    assert_equal( (i * -2).to_s, "-1.0" )
 
   end
 
@@ -203,7 +209,9 @@ class DBTrans_TestClass < TestBase
     assert_equal( (c.angle - 45).abs < 1e-10, true )
 
     assert_equal( c.ctrans( 5 ).to_s, "3.75" )
+    assert_equal( c.ctrans( -5 ).to_s, "-3.75" )
     assert_equal( (c * 5).to_s, "3.75" )
+    assert_equal( (c * -5).to_s, "-3.75" )
     assert_equal( c.trans( RBA::DPoint::new( 12, 16 ) ).to_s, "17.3492424049,-14.6213203436" )
 
     assert_equal( RBA::DCplxTrans::new.to_s, "r0 *1 0,0" )
@@ -270,6 +278,11 @@ class DBTrans_TestClass < TestBase
     c.mirror = true
     assert_equal( c.to_s, "m135 1,7" )
 
+    assert_equal( e.ctrans( 2 ), 2 )
+    assert_equal( e.ctrans( -2 ), -2 )
+    assert_equal( e * 2, 2 )
+    assert_equal( e * -2, -2 )
+
     assert_equal( e.trans( RBA::Edge::new(0, 1, 2, 3) ).to_s, "(-3,-2;-1,0)" )
     assert_equal( ( e * RBA::Edge::new(0, 1, 2, 3) ).to_s, "(-3,-2;-1,0)" )
     assert_equal( e.trans( RBA::Box::new(0, 1, 2, 3) ).to_s, "(-3,-2;-1,0)" )
@@ -311,9 +324,13 @@ class DBTrans_TestClass < TestBase
 
     assert_equal( mb.trans( RBA::Point::new( 1, 0 )).to_s, "17,3" )
     assert_equal( mb.ctrans(2).to_s, "4.0" )
+    assert_equal( mb.ctrans(-2).to_s, "-4.0" )
     assert_equal( (mb * 2).to_s, "4.0" )
+    assert_equal( (mb * -2).to_s, "-4.0" )
     assert_equal( i.ctrans(2).to_s, "1.0" )
+    assert_equal( i.ctrans(-2).to_s, "-1.0" )
     assert_equal( (i * 2).to_s, "1.0" )
+    assert_equal( (i * -2).to_s, "-1.0" )
 
   end
 
@@ -360,7 +377,9 @@ class DBTrans_TestClass < TestBase
     assert_equal( (c.angle - 45).abs < 1e-10, true )
 
     assert_equal( c.ctrans( 5 ).to_s, "3.75" )
+    assert_equal( c.ctrans( -5 ).to_s, "-3.75" )
     assert_equal( (c * 5).to_s, "3.75" )
+    assert_equal( (c * -5).to_s, "-3.75" )
     assert_equal( c.trans( RBA::Point::new( 12, 16 ) ).to_s, "17.3492424049,-14.6213203436" )
 
     assert_equal( RBA::CplxTrans::new.to_s, "r0 *1 0,0" )