diff --git a/src/common/tarstrm.cpp b/src/common/tarstrm.cpp
index fb4011cb96..f0fff936b1 100644
--- a/src/common/tarstrm.cpp
+++ b/src/common/tarstrm.cpp
@@ -133,7 +133,7 @@ public:
 
     bool Read(wxInputStream& in);
     bool Write(wxOutputStream& out);
-    bool WriteField(wxOutputStream& out, int id);
+    inline bool WriteField(wxOutputStream& out, int id);
 
     bool IsAllZeros() const;
     wxUint32 Sum(bool SignedSum = false);
@@ -247,7 +247,7 @@ bool wxTarHeaderBlock::Write(wxOutputStream& out)
     return ok;
 }
 
-bool wxTarHeaderBlock::WriteField(wxOutputStream& out, int id)
+inline bool wxTarHeaderBlock::WriteField(wxOutputStream& out, int id)
 {
     return out.Write(Get(id), Len(id)).LastWrite() == Len(id);
 }
diff --git a/src/common/zipstrm.cpp b/src/common/zipstrm.cpp
index fae269024c..aa3568f0d5 100644
--- a/src/common/zipstrm.cpp
+++ b/src/common/zipstrm.cpp
@@ -173,9 +173,9 @@ class wxZipHeader
 public:
     wxZipHeader(wxInputStream& stream, size_t size);
 
-    wxUint8 Read8();
-    wxUint16 Read16();
-    wxUint32 Read32();
+    inline wxUint8 Read8();
+    inline wxUint16 Read16();
+    inline wxUint32 Read32();
 
     const char *GetData() const             { return m_data; }
     size_t GetSize() const                  { return m_size; }
@@ -205,13 +205,13 @@ wxZipHeader::wxZipHeader(wxInputStream& stream, size_t size)
     m_ok = m_size == size;
 }
 
-wxUint8 wxZipHeader::Read8()
+inline wxUint8 wxZipHeader::Read8()
 {
     wxASSERT(m_pos < m_size);
     return m_data[m_pos++];
 }
 
-wxUint16 wxZipHeader::Read16()
+inline wxUint16 wxZipHeader::Read16()
 {
     wxASSERT(m_pos + 2 <= m_size);
     wxUint16 n = CrackUint16(m_data + m_pos);
@@ -219,7 +219,7 @@ wxUint16 wxZipHeader::Read16()
     return n;
 }
 
-wxUint32 wxZipHeader::Read32()
+inline wxUint32 wxZipHeader::Read32()
 {
     wxASSERT(m_pos + 4 <= m_size);
     wxUint32 n = CrackUint32(m_data + m_pos);
diff --git a/src/msw/registry.cpp b/src/msw/registry.cpp
index 3c31939c81..32d0d28510 100644
--- a/src/msw/registry.cpp
+++ b/src/msw/registry.cpp
@@ -108,7 +108,7 @@ aStdKeys[] =
 // ----------------------------------------------------------------------------
 
 // removes the trailing backslash from the string if it has one
-static void RemoveTrailingSeparator(wxString& str);
+static inline void RemoveTrailingSeparator(wxString& str);
 
 // returns true if given registry key exists
 static bool KeyExists(WXHKEY hRootKey, const wxChar *szKey);
@@ -1413,7 +1413,7 @@ const wxChar *GetFullName(const wxRegKey *pKey, const wxChar *szValue)
   return s_str.c_str();
 }
 
-void RemoveTrailingSeparator(wxString& str)
+inline void RemoveTrailingSeparator(wxString& str)
 {
   if ( !str.empty() && str.Last() == REG_SEPARATOR )
     str.Truncate(str.Len() - 1);