diff --git a/aspectratio.h b/aspectratio.h
index 937910f..42ff466 100644
--- a/aspectratio.h
+++ b/aspectratio.h
@@ -8,11 +8,11 @@
 namespace Media {
 
 struct TAG_PARSER_EXPORT AspectRatio {
-    AspectRatio();
+    constexpr AspectRatio();
     AspectRatio(byte aspectRatioType);
-    AspectRatio(uint16 numerator, uint16 denominator);
-    bool isValid() const;
-    bool isExtended() const;
+    constexpr AspectRatio(uint16 numerator, uint16 denominator);
+    constexpr bool isValid() const;
+    constexpr bool isExtended() const;
 
     byte type;
     uint16 numerator;
@@ -22,7 +22,7 @@ struct TAG_PARSER_EXPORT AspectRatio {
 /*!
  * \brief Constructs an invalid aspect ratio.
  */
-inline  AspectRatio::AspectRatio() :
+constexpr AspectRatio::AspectRatio() :
     type(0),
     numerator(0),
     denominator(0)
@@ -31,7 +31,7 @@ inline  AspectRatio::AspectRatio() :
 /*!
  * \brief Constructs a aspect ratio with the specified \a numerator and \a denominator.
  */
-inline AspectRatio::AspectRatio(uint16 numerator, uint16 denominator) :
+constexpr AspectRatio::AspectRatio(uint16 numerator, uint16 denominator) :
     type(0xFF),
     numerator(numerator),
     denominator(denominator)
@@ -40,7 +40,7 @@ inline AspectRatio::AspectRatio(uint16 numerator, uint16 denominator) :
 /*!
  * \brief Returns an indication whether the aspect ratio is present and valid.
  */
-inline bool AspectRatio::isValid() const
+constexpr bool AspectRatio::isValid() const
 {
     return type && numerator && denominator;
 }
@@ -48,7 +48,7 @@ inline bool AspectRatio::isValid() const
 /*!
  * \brief Returns whether numerator and denominator must be read from extended SAR header.
  */
-inline bool AspectRatio::isExtended() const
+constexpr bool AspectRatio::isExtended() const
 {
     return type == 0xFF;
 }
diff --git a/genericfileelement.h b/genericfileelement.h
index 3cfac6c..aa827fa 100644
--- a/genericfileelement.h
+++ b/genericfileelement.h
@@ -911,7 +911,7 @@ typename GenericFileElement<ImplementationType>::implementationType *GenericFile
  * \brief Returns the maximum id length supported by the class in byte.
  */
 template <class ImplementationType>
-inline constexpr uint32 GenericFileElement<ImplementationType>::maximumIdLengthSupported()
+constexpr uint32 GenericFileElement<ImplementationType>::maximumIdLengthSupported()
 {
     return sizeof(identifierType);
 }
@@ -920,7 +920,7 @@ inline constexpr uint32 GenericFileElement<ImplementationType>::maximumIdLengthS
  * \brief Returns the maximum size length supported by the class in byte.
  */
 template <class ImplementationType>
-inline constexpr uint32 GenericFileElement<ImplementationType>::maximumSizeLengthSupported()
+constexpr uint32 GenericFileElement<ImplementationType>::maximumSizeLengthSupported()
 {
     return sizeof(dataSizeType);
 }
@@ -929,7 +929,7 @@ inline constexpr uint32 GenericFileElement<ImplementationType>::maximumSizeLengt
  * \brief Returns the mimimum element size.
  */
 template <class ImplementationType>
-inline constexpr byte GenericFileElement<ImplementationType>::minimumElementSize()
+constexpr byte GenericFileElement<ImplementationType>::minimumElementSize()
 {
     return FileElementTraits<ImplementationType>::minimumElementSize();
 }
diff --git a/margin.h b/margin.h
index 43ce92b..68b4fd4 100644
--- a/margin.h
+++ b/margin.h
@@ -48,7 +48,7 @@ constexpr Margin::Margin(uint32 top, uint32 left, uint32 bottom, uint32 right) :
 /*!
  * \brief Returns the top margin.
  */
-inline constexpr uint32 Margin::top() const
+constexpr uint32 Margin::top() const
 {
     return m_top;
 }
@@ -64,7 +64,7 @@ inline void Margin::setTop(uint32 top)
 /*!
  * \brief Returns the left margin.
  */
-inline constexpr uint32 Margin::left() const
+constexpr uint32 Margin::left() const
 {
     return m_left;
 }
@@ -80,7 +80,7 @@ inline void Margin::setLeft(uint32 left)
 /*!
  * \brief Returns the bottom margin.
  */
-inline constexpr uint32 Margin::bottom() const
+constexpr uint32 Margin::bottom() const
 {
     return m_bottom;
 }
@@ -96,7 +96,7 @@ inline void Margin::setBottom(uint32 bottom)
 /*!
  * \brief Returns the right margin.
  */
-inline constexpr uint32 Margin::right() const
+constexpr uint32 Margin::right() const
 {
     return m_right;
 }
@@ -112,7 +112,7 @@ inline void Margin::setRight(uint32 right)
 /*!
  * \brief Returns true if all margins are is 0; otherwise returns false;
  */
-inline constexpr bool Margin::isNull() const
+constexpr bool Margin::isNull() const
 {
     return m_top == 0 && m_left == 0 && m_bottom == 0 && m_right == 0;
 }
diff --git a/size.h b/size.h
index 7700967..4e24109 100644
--- a/size.h
+++ b/size.h
@@ -52,7 +52,7 @@ constexpr Size::Size(uint32 width, uint32 height) :
 /*!
  * \brief Returns the width.
  */
-inline constexpr uint32 Size::width() const
+constexpr uint32 Size::width() const
 {
     return m_width;
 }
@@ -60,7 +60,7 @@ inline constexpr uint32 Size::width() const
 /*!
  * \brief Returns the height.
  */
-inline constexpr uint32 Size::height() const
+constexpr uint32 Size::height() const
 {
     return m_height;
 }
@@ -84,7 +84,7 @@ inline void Size::setHeight(uint32 value)
 /*!
  * \brief Returns an indication whether both the width and height is 0.
  */
-inline constexpr bool Size::isNull() const
+constexpr bool Size::isNull() const
 {
     return (m_width == 0) && (m_height == 0);
 }
@@ -92,7 +92,7 @@ inline constexpr bool Size::isNull() const
 /*!
  * \brief Returns whether this instance equals \a other.
  */
-inline constexpr bool Size::operator==(const Size &other) const
+constexpr bool Size::operator==(const Size &other) const
 {
     return (m_width == other.m_width) && (m_height == other.m_height);
 }