diff --git a/ZRCola/zrcolacomppnl.cpp b/ZRCola/zrcolacomppnl.cpp
index 21125f9..a10e868 100644
--- a/ZRCola/zrcolacomppnl.cpp
+++ b/ZRCola/zrcolacomppnl.cpp
@@ -51,7 +51,7 @@ void wxZRColaComposerPanel::OnDecomposedPaint(wxPaintEvent& event)
         // Save new selection first, to avoid loop.
         m_selDecomposed.first  = from;
         m_selDecomposed.second = to;
-        m_composed->SetSelection(m_mapping.to_composed(from), m_mapping.to_composed(to));
+        m_composed->SetSelection(m_mapping.to_src(from), m_mapping.to_src(to));
     }
 }
 
@@ -73,6 +73,7 @@ void wxZRColaComposerPanel::OnDecomposedText(wxCommandEvent& event)
 
         std::wstring dst;
         ((ZRColaApp*)wxTheApp)->m_t_db.Compose(src.data(), src.size(), dst, &m_mapping);
+        m_mapping.invert();
 
         long from, to;
         m_decomposed->GetSelection(&from, &to);
@@ -80,7 +81,7 @@ void wxZRColaComposerPanel::OnDecomposedText(wxCommandEvent& event)
         // Update composed text.
         m_progress = true;
         m_composed->SetValue(dst);
-        m_composed->SetSelection(m_mapping.to_composed(from), m_mapping.to_composed(to));
+        m_composed->SetSelection(m_mapping.to_src(from), m_mapping.to_src(to));
         event.Skip();
         m_progress = false;
     }
@@ -98,7 +99,7 @@ void wxZRColaComposerPanel::OnComposedPaint(wxPaintEvent& event)
         // Save new selection first, to avoid loop.
         m_selComposed.first  = from;
         m_selComposed.second = to;
-        m_decomposed->SetSelection(m_mapping.to_decomposed(from), m_mapping.to_decomposed(to));
+        m_decomposed->SetSelection(m_mapping.to_dst(from), m_mapping.to_dst(to));
     }
 }
 
@@ -132,7 +133,7 @@ void wxZRColaComposerPanel::OnComposedText(wxCommandEvent& event)
         // Update decomposed text.
         m_progress = true;
         m_decomposed->SetValue(dst);
-        m_decomposed->SetSelection(m_mapping.to_decomposed(from), m_mapping.to_decomposed(to));
+        m_decomposed->SetSelection(m_mapping.to_dst(from), m_mapping.to_dst(to));
         event.Skip();
         m_progress = false;
     }
diff --git a/lib/libZRCola/include/zrcola/common.h b/lib/libZRCola/include/zrcola/common.h
index 0d33fe7..be73110 100644
--- a/lib/libZRCola/include/zrcola/common.h
+++ b/lib/libZRCola/include/zrcola/common.h
@@ -223,15 +223,20 @@ namespace ZRCola {
 
 
     ///
-    /// Composed-decomposed index transformation mapping
+    /// Source-destination index transformation mapping
     ///
     class ZRCOLA_NOVTABLE ZRCOLA_API mapping {
     public:
-        size_t cmp;     ///< Character index in composed string
-        size_t decmp;   ///< Character index in decomposed string
+        size_t src;     ///< Character index in source string
+        size_t dst;     ///< Character index in destination string
 
         inline mapping() {};
-        inline mapping(_In_ size_t c, _In_ size_t d) : cmp(c), decmp(d) {}
+        inline mapping(_In_ size_t s, _In_ size_t d) : src(s), dst(d) {}
+
+        ///
+        /// Reverses source and destination indexes
+        ///
+        inline void invert() { size_t tmp = src; src = dst; dst = tmp; }
     };
 
 
@@ -241,22 +246,31 @@ namespace ZRCola {
     class ZRCOLA_API mapping_vector : public std::vector<mapping> {
     public:
         ///
-        /// Transforms character index of decomposed to composed string
+        /// Transforms character index of destination to source
         ///
-        /// \param[in] decmp  Character index in decomposed string
+        /// \param[in] decmp  Character index in destination string
         ///
-        /// \returns  Character index in composed string
+        /// \returns  Character index in source string
         ///
-        size_t to_composed(_In_ size_t decmp) const;
+        size_t to_src(_In_ size_t dst) const;
 
         ///
-        /// Transforms destination index to source index
+        /// Transforms source index to destination index
         ///
-        /// \param[in] cmp  Character index in composed string
+        /// \param[in] cmp  Character index in source string
         ///
-        /// \returns  Character index in decomposed string
+        /// \returns  Character index in destination string
         ///
-        size_t to_decomposed(_In_ size_t cmp) const;
+        size_t to_dst(_In_ size_t src) const;
+
+        ///
+        /// Reverses source and destination indexes
+        ///
+        inline void invert()
+        {
+            for (iterator i = begin(), iEnd = end(); i != iEnd; ++i)
+                i->invert();
+        }
     };
 };
 
diff --git a/lib/libZRCola/src/mapping.cpp b/lib/libZRCola/src/mapping.cpp
index 460562e..85e8144 100644
--- a/lib/libZRCola/src/mapping.cpp
+++ b/lib/libZRCola/src/mapping.cpp
@@ -20,51 +20,51 @@
 #include "stdafx.h"
 
 
-size_t ZRCola::mapping_vector::to_composed(_In_ size_t decmp) const
+size_t ZRCola::mapping_vector::to_src(_In_ size_t dst) const
 {
     for (size_type l = 0, r = size();;) {
         if (l < r) {
             size_type m = (l + r) / 2;
             const mapping &el = (*this)[m];
 
-                 if (decmp < el.decmp) r = m;
-            else if (el.decmp < decmp) l = m + 1;
+                 if (   dst < el.dst) r = m;
+            else if (el.dst <    dst) l = m + 1;
             else {
                 // An exact match found.
-                return el.cmp;
+                return el.src;
             }
         } else if (l) {
             // We found a map interval.
             const mapping &el = (*this)[l - 1];
-            return el.cmp + (decmp - el.decmp);
+            return el.src + (dst - el.dst);
         } else {
-            // The decomposed character index is far left.
-            return decmp;
+            // The destination character index is far left.
+            return dst;
         }
     }
 }
 
 
-size_t ZRCola::mapping_vector::to_decomposed(_In_ size_t cmp) const
+size_t ZRCola::mapping_vector::to_dst(_In_ size_t src) const
 {
     for (size_type l = 0, r = size();;) {
         if (l < r) {
             size_type m = (l + r) / 2;
             const mapping &el = (*this)[m];
 
-                 if (cmp < el.cmp) r = m;
-            else if (el.cmp < cmp) l = m + 1;
+                 if (   src < el.src) r = m;
+            else if (el.src <    src) l = m + 1;
             else {
                 // An exact match found.
-                return el.decmp;
+                return el.dst;
             }
         } else if (l) {
             // We found a map interval.
             const mapping &el = (*this)[l - 1];
-            return el.decmp + (cmp - el.cmp);
+            return el.dst + (src - el.src);
         } else {
-            // The composed character index is far left.
-            return cmp;
+            // The source character index is far left.
+            return src;
         }
     }
 }
diff --git a/lib/libZRCola/src/translate.cpp b/lib/libZRCola/src/translate.cpp
index 82830cb..2ecb719 100644
--- a/lib/libZRCola/src/translate.cpp
+++ b/lib/libZRCola/src/translate.cpp
@@ -91,7 +91,7 @@ void ZRCola::translation_db::Compose(_In_z_count_(inputMax) const wchar_t* input
             i += trans.str_len;
             if (trans.str_len > 1 && map) {
                 // Mapping changed.
-                map->push_back(ZRCola::mapping(output.length(), i));
+                map->push_back(ZRCola::mapping(i, output.length()));
             }
         } else {
             // The match was not found.