diff --git a/src/FTContour.cpp b/src/FTContour.cpp
index c668d32..ef13576 100644
--- a/src/FTContour.cpp
+++ b/src/FTContour.cpp
@@ -174,7 +174,7 @@ void FTContour::SetParity(int parity)
 }
 
 
-FTContour::FTContour(FT_Vector* contour, char* tags, unsigned int n)
+FTContour::FTContour(FT_Vector* contour, unsigned char* tags, unsigned int n)
 {
     FTPoint prev, cur(contour[(n - 1) % n]), next(contour[0]);
     double olddir, dir = atan2((next - cur).Y(), (next - cur).X());
diff --git a/src/FTContour.h b/src/FTContour.h
index d2d187c..dc64e3a 100644
--- a/src/FTContour.h
+++ b/src/FTContour.h
@@ -52,7 +52,7 @@ class FTContour
          * @param pointTags
          * @param numberOfPoints
          */
-        FTContour(FT_Vector* contour, char* pointTags, unsigned int numberOfPoints);
+        FTContour(FT_Vector* contour, unsigned char* pointTags, unsigned int numberOfPoints);
 
         /**
          * Destructor
diff --git a/src/FTVectoriser.cpp b/src/FTVectoriser.cpp
index 26e7da8..53d738e 100644
--- a/src/FTVectoriser.cpp
+++ b/src/FTVectoriser.cpp
@@ -168,7 +168,7 @@ void FTVectoriser::ProcessContours()
     for(int i = 0; i < ftContourCount; ++i)
     {
         FT_Vector* pointList = &outline.points[startIndex];
-        char* tagList = &outline.tags[startIndex];
+        unsigned char* tagList = &outline.tags[startIndex];
 
         endIndex = outline.contours[i];
         contourLength =  (endIndex - startIndex) + 1;