diff --git a/CHANGES.md b/CHANGES.md
index a88dcfd..679fbe4 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -5,6 +5,7 @@ Changes in PDFio
 v1.2.0 (Month DD, YYYY)
 -----------------------
 
+- Added `pdfioContentTextMeasure` function (Issue #17)
 - Now use autoconf to configure the PDFio sources (Issue #54)
 
 
diff --git a/pdfio1.def b/pdfio1.def
index c9dabe5..c487d01 100644
--- a/pdfio1.def
+++ b/pdfio1.def
@@ -47,7 +47,9 @@ _pdfioFileSeek
 _pdfioFileTell
 _pdfioFileWrite
 _pdfioObjDelete
+_pdfioObjGetExtension
 _pdfioObjLoad
+_pdfioObjSetExtension
 _pdfioStreamCreate
 _pdfioStreamOpen
 _pdfioStringIsAllocated
@@ -136,6 +138,7 @@ pdfioContentSetTextXScaling
 pdfioContentStroke
 pdfioContentTextBegin
 pdfioContentTextEnd
+pdfioContentTextMeasure
 pdfioContentTextMoveLine
 pdfioContentTextMoveTo
 pdfioContentTextNextLine