diff --git a/src/gmio_core/internal/fast_atof.h b/src/gmio_core/internal/fast_atof.h
index 1de35fb..ceeeac9 100644
--- a/src/gmio_core/internal/fast_atof.h
+++ b/src/gmio_core/internal/fast_atof.h
@@ -4,14 +4,20 @@
  * and irrXML.h
  */
 
-/* Adapted to ISO-C90 */
+/* Adapted to ISO-C90.
+ *
+ * WARNING :
+ *     this header has no multi-inclusion guard. It must be included only once
+ *     in the translation unit of use. The reason is that all functions
+ *     defined here are meant to be inlined for performance purpose
+ */
 
 #include "../global.h"
 
 #include <float.h>
 #include <limits.h>
 
-GMIO_INLINE gmio_bool_t is_local_decimal_point(char in)
+GMIO_INLINE static gmio_bool_t is_local_decimal_point(char in)
 {
     /*! Selection of characters which count as decimal point in fast_atof
      * TODO: This should probably also be used in irr::core::string, but
@@ -54,7 +60,7 @@ const float fast_atof_table[17] = {
  * \return The unsigned integer value of the digits. If the string specifies
  * too many digits to encode in an uint32_t then INT_MAX will be returned.
  */
-GMIO_INLINE uint32_t strtoul10(const char* in, const char** out)
+GMIO_INLINE static uint32_t strtoul10(const char* in, const char** out)
 {
     gmio_bool_t overflow=GMIO_FALSE;
     uint32_t unsignedValue = 0;
@@ -93,7 +99,7 @@ GMIO_INLINE uint32_t strtoul10(const char* in, const char** out)
  * too many digits to encode in an int32_t then +INT_MAX or -INT_MAX will be
  * returned.
  */
-GMIO_INLINE int32_t strtol10(const char* in, const char** out)
+GMIO_INLINE static int32_t strtol10(const char* in, const char** out)
 {
     const gmio_bool_t negative = ('-' == *in);
     uint32_t unsignedValue = 0;
@@ -130,7 +136,7 @@ GMIO_INLINE int32_t strtol10(const char* in, const char** out)
  * \return The unsigned integer value of the digit. 0xffffffff if the input is
  * not hex
  */
-GMIO_INLINE uint32_t ctoul16(char in)
+GMIO_INLINE static uint32_t ctoul16(char in)
 {
     if (in >= '0' && in <= '9')
         return in - '0';
@@ -152,7 +158,7 @@ GMIO_INLINE uint32_t ctoul16(char in)
  * \return The unsigned integer value of the digits. If the string specifies
  * too many digits to encode in an uint32_t then INT_MAX will be returned.
  */
-GMIO_INLINE uint32_t strtoul16(const char* in, const char** out)
+GMIO_INLINE static uint32_t strtoul16(const char* in, const char** out)
 {
     gmio_bool_t overflow=GMIO_FALSE;
     uint32_t unsignedValue = 0;
@@ -197,7 +203,7 @@ GMIO_INLINE uint32_t strtoul16(const char* in, const char** out)
  * \return The unsigned integer value of the digits. If the string specifies
  * too many digits to encode in an uint32_t then INT_MAX will be returned.
  */
-GMIO_INLINE uint32_t strtoul8(const char* in, const char** out)
+GMIO_INLINE static uint32_t strtoul8(const char* in, const char** out)
 {
     gmio_bool_t overflow=GMIO_FALSE;
     uint32_t unsignedValue = 0;
@@ -239,7 +245,7 @@ GMIO_INLINE uint32_t strtoul8(const char* in, const char** out)
  * \return The unsigned integer value of the digits. If the string specifies
  * too many digits to encode in an uint32_t then INT_MAX will be returned.
  */
-GMIO_INLINE uint32_t strtoul_prefix(const char* in, const char** out)
+GMIO_INLINE static uint32_t strtoul_prefix(const char* in, const char** out)
 {
     if (!in)
     {
@@ -262,7 +268,7 @@ GMIO_INLINE uint32_t strtoul_prefix(const char* in, const char** out)
  * \return The whole positive floating point representation of the digit
  * sequence.
  */
-GMIO_INLINE gmio_float32_t strtof10(const char* in, const char** out)
+GMIO_INLINE static gmio_float32_t strtof10(const char* in, const char** out)
 {
     const uint32_t MAX_SAFE_U32_VALUE = UINT_MAX / 10 - 10;
     uint32_t intValue = 0;
@@ -309,7 +315,8 @@ GMIO_INLINE gmio_float32_t strtof10(const char* in, const char** out)
  * \return Pointer to the first character in the string that wasn't used
  * to create the float value.
  */
-GMIO_INLINE const char* fast_atof_move(const char* in, gmio_float32_t* result)
+GMIO_INLINE static const char* fast_atof_move(
+        const char* in, gmio_float32_t* result)
 {
     const gmio_bool_t negative = ('-' == *in);
     gmio_float32_t value = 0.f;
@@ -353,7 +360,7 @@ GMIO_INLINE const char* fast_atof_move(const char* in, gmio_float32_t* result)
  * wasn't used to create the float value.
  * \result Float value parsed from the input string
  */
-GMIO_INLINE float fast_atof(const char* floatAsString, const char** out)
+GMIO_INLINE static float fast_atof(const char* floatAsString, const char** out)
 {
     float ret;
     if (out)
diff --git a/src/gmio_core/internal/helper_error.h b/src/gmio_core/internal/helper_error.h
index ca16a2c..136c09f 100644
--- a/src/gmio_core/internal/helper_error.h
+++ b/src/gmio_core/internal/helper_error.h
@@ -22,13 +22,13 @@
 #include "../error.h"
 
 /*! Returns true if <tt>code == GMIO_NO_ERROR</tt> */
-GMIO_INLINE gmio_bool_t gmio_no_error(int code)
+GMIO_INLINE static gmio_bool_t gmio_no_error(int code)
 {
     return code == GMIO_NO_ERROR;
 }
 
 /*! Returns true if <tt>code != GMIO_NO_ERROR</tt> */
-GMIO_INLINE gmio_bool_t gmio_error(int code)
+GMIO_INLINE static gmio_bool_t gmio_error(int code)
 {
     return code != GMIO_NO_ERROR;
 }
diff --git a/src/gmio_core/internal/helper_stream.h b/src/gmio_core/internal/helper_stream.h
index 17eeb76..797aa84 100644
--- a/src/gmio_core/internal/helper_stream.h
+++ b/src/gmio_core/internal/helper_stream.h
@@ -22,7 +22,7 @@
 #include "../stream.h"
 
 /*! Safe and convenient function for gmio_stream::at_end_func() */
-GMIO_INLINE gmio_bool_t gmio_stream_at_end(gmio_stream_t* stream)
+GMIO_INLINE static gmio_bool_t gmio_stream_at_end(gmio_stream_t* stream)
 {
     if (stream != NULL && stream->at_end_func != NULL)
         return stream->at_end_func(stream->cookie);
@@ -30,7 +30,7 @@ GMIO_INLINE gmio_bool_t gmio_stream_at_end(gmio_stream_t* stream)
 }
 
 /*! Safe and convenient function for gmio_stream::error_func()  */
-GMIO_INLINE int gmio_stream_error(gmio_stream_t* stream)
+GMIO_INLINE static int gmio_stream_error(gmio_stream_t* stream)
 {
     if (stream != NULL && stream->error_func != NULL)
         return stream->error_func(stream->cookie);
@@ -38,7 +38,7 @@ GMIO_INLINE int gmio_stream_error(gmio_stream_t* stream)
 }
 
 /*! Safe and convenient function for gmio_stream::read_func() */
-GMIO_INLINE size_t gmio_stream_read(
+GMIO_INLINE static size_t gmio_stream_read(
         gmio_stream_t* stream, void *ptr, size_t size, size_t count)
 {
     if (stream != NULL && stream->read_func != NULL)
@@ -47,7 +47,7 @@ GMIO_INLINE size_t gmio_stream_read(
 }
 
 /*! Safe and convenient function for gmio_stream::write_func() */
-GMIO_INLINE size_t gmio_stream_write(
+GMIO_INLINE static size_t gmio_stream_write(
         gmio_stream_t* stream, const void *ptr, size_t size, size_t count)
 {
     if (stream != NULL && stream->write_func != NULL)
@@ -56,7 +56,7 @@ GMIO_INLINE size_t gmio_stream_write(
 }
 
 /*! Safe and convenient function for gmio_stream::size_func() */
-GMIO_INLINE size_t gmio_stream_size(gmio_stream_t* stream)
+GMIO_INLINE static size_t gmio_stream_size(gmio_stream_t* stream)
 {
     if (stream != NULL && stream->size_func != NULL)
         return stream->size_func(stream->cookie);
@@ -64,7 +64,7 @@ GMIO_INLINE size_t gmio_stream_size(gmio_stream_t* stream)
 }
 
 /*! Safe and convenient function for gmio_stream::rewind_func() */
-GMIO_INLINE void gmio_stream_rewind(gmio_stream_t* stream)
+GMIO_INLINE static void gmio_stream_rewind(gmio_stream_t* stream)
 {
     if (stream != NULL && stream->rewind_func != NULL)
         stream->rewind_func(stream->cookie);
diff --git a/src/gmio_core/internal/helper_transfer.h b/src/gmio_core/internal/helper_transfer.h
index eeaee5d..78e0fb3 100644
--- a/src/gmio_core/internal/helper_transfer.h
+++ b/src/gmio_core/internal/helper_transfer.h
@@ -24,7 +24,7 @@
 #include <stddef.h>
 
 /*! Safe and convenient function for gmio_transfer::is_stop_requested_func() */
-GMIO_INLINE gmio_bool_t gmio_transfer_is_stop_requested(
+GMIO_INLINE static gmio_bool_t gmio_transfer_is_stop_requested(
         const gmio_transfer_t* trsf)
 {
     if (trsf != NULL && trsf->is_stop_requested_func != NULL)
@@ -33,7 +33,7 @@ GMIO_INLINE gmio_bool_t gmio_transfer_is_stop_requested(
 }
 
 /*! Safe and convenient function for gmio_transfer::handle_progress_func() */
-GMIO_INLINE void gmio_transfer_handle_progress(
+GMIO_INLINE static void gmio_transfer_handle_progress(
         const gmio_transfer_t* trsf, size_t value, size_t max_value)
 {
     if (trsf != NULL && trsf->handle_progress_func != NULL)
diff --git a/src/gmio_stl/internal/helper_stl_mesh_creator.h b/src/gmio_stl/internal/helper_stl_mesh_creator.h
index 23e4e67..17f26de 100644
--- a/src/gmio_stl/internal/helper_stl_mesh_creator.h
+++ b/src/gmio_stl/internal/helper_stl_mesh_creator.h
@@ -23,7 +23,7 @@
 
 /*! Safe and convenient function for
  *  gmio_stl_mesh_creator::ascii_begin_solid_func() */
-GMIO_INLINE void gmio_stl_mesh_creator_ascii_begin_solid(
+GMIO_INLINE static void gmio_stl_mesh_creator_ascii_begin_solid(
         gmio_stl_mesh_creator_t* creator,
         size_t stream_size,
         const char* solid_name)
@@ -36,7 +36,7 @@ GMIO_INLINE void gmio_stl_mesh_creator_ascii_begin_solid(
 
 /*! Safe and convenient function for
  *  gmio_stl_mesh_creator::binary_begin_solid_func() */
-GMIO_INLINE void gmio_stl_mesh_creator_binary_begin_solid(
+GMIO_INLINE static void gmio_stl_mesh_creator_binary_begin_solid(
         gmio_stl_mesh_creator_t* creator,
         uint32_t tri_count,
         const uint8_t* header)
@@ -47,7 +47,7 @@ GMIO_INLINE void gmio_stl_mesh_creator_binary_begin_solid(
 
 /*! Safe and convenient function for
  *  gmio_stl_mesh_creator::add_triangle_func() */
-GMIO_INLINE void gmio_stl_mesh_creator_add_triangle(
+GMIO_INLINE static void gmio_stl_mesh_creator_add_triangle(
         gmio_stl_mesh_creator_t* creator,
         uint32_t tri_id,
         const gmio_stl_triangle_t* triangle)
@@ -58,7 +58,7 @@ GMIO_INLINE void gmio_stl_mesh_creator_add_triangle(
 
 /*! Safe and convenient function for
  *  gmio_stl_mesh_creator::end_solid_func() */
-GMIO_INLINE void gmio_stl_mesh_creator_end_solid(
+GMIO_INLINE static void gmio_stl_mesh_creator_end_solid(
         gmio_stl_mesh_creator_t* creator)
 {
     if (creator != NULL && creator->end_solid_func != NULL)
diff --git a/src/gmio_stl/stla_read.c b/src/gmio_stl/stla_read.c
index 44383d0..e070020 100644
--- a/src/gmio_stl/stla_read.c
+++ b/src/gmio_stl/stla_read.c
@@ -239,7 +239,7 @@ static gmio_stla_token_t parsing_find_token(
     return ID_token;
 }
 
-static void parsing_advance(gmio_stla_parse_data_t* data)
+GMIO_INLINE static void parsing_advance(gmio_stla_parse_data_t* data)
 {
     if (!parsing_can_continue(data))
         return;
@@ -253,7 +253,7 @@ static void parsing_advance(gmio_stla_parse_data_t* data)
         parsing_error(data);
 }
 
-static void parsing_eat_token(
+GMIO_INLINE static void parsing_eat_token(
         gmio_stla_token_t token, gmio_stla_parse_data_t* data)
 {
     if (!parsing_can_continue(data))