diff --git a/features/filesystem/File.h b/features/filesystem/File.h
index 5043ba1b5f..700c241634 100644
--- a/features/filesystem/File.h
+++ b/features/filesystem/File.h
@@ -75,7 +75,7 @@ public:
      *  @return         The number of bytes read, 0 at end of file, negative error on failure
      */
 
-    virtual ssize_t read(void *buffer, size_t len);
+    virtual ssize_t read(void *buffer, size_t size);
 
     /** Write the contents of a buffer to a file
      *
@@ -83,7 +83,7 @@ public:
      *  @param size     The number of bytes to write 
      *  @return         The number of bytes written, negative error on failure
      */
-    virtual ssize_t write(const void *buffer, size_t len);
+    virtual ssize_t write(const void *buffer, size_t size);
 
     /** Flush any buffers associated with the file
      *
diff --git a/features/filesystem/FileSystem.h b/features/filesystem/FileSystem.h
index d5824b60b1..ca7597282d 100644
--- a/features/filesystem/FileSystem.h
+++ b/features/filesystem/FileSystem.h
@@ -118,7 +118,7 @@ protected:
      *  @param size     The number of bytes to read
      *  @return         The number of bytes read, 0 at end of file, negative error on failure
      */
-    virtual ssize_t file_read(fs_file_t file, void *buffer, size_t len) = 0;
+    virtual ssize_t file_read(fs_file_t file, void *buffer, size_t size) = 0;
 
     /** Write the contents of a buffer to a file
      *
@@ -127,7 +127,7 @@ protected:
      *  @param size     The number of bytes to write 
      *  @return         The number of bytes written, negative error on failure
      */
-    virtual ssize_t file_write(fs_file_t file, const void *buffer, size_t len) = 0;
+    virtual ssize_t file_write(fs_file_t file, const void *buffer, size_t size) = 0;
 
     /** Flush any buffers associated with the file
      *
diff --git a/platform/FileHandle.h b/platform/FileHandle.h
index 13947a936c..e131599600 100644
--- a/platform/FileHandle.h
+++ b/platform/FileHandle.h
@@ -45,7 +45,7 @@ public:
      *  @param size     The number of bytes to read
      *  @return         The number of bytes read, 0 at end of file, negative error on failure
      */
-    virtual ssize_t read(void *buffer, size_t len) = 0;
+    virtual ssize_t read(void *buffer, size_t size) = 0;
 
     /** Write the contents of a buffer to a file
      *
@@ -53,7 +53,7 @@ public:
      *  @param size     The number of bytes to write 
      *  @return         The number of bytes written, negative error on failure
      */
-    virtual ssize_t write(const void *buffer, size_t len) = 0;
+    virtual ssize_t write(const void *buffer, size_t size) = 0;
 
     /** Move the file position to a given offset from from a given location
      *