1 files changed, 3 insertions, 3 deletions
diff --git a/converter/pgm/st4topgm.c b/converter/pgm/st4topgm.c
index 90be6b72..791184b7 100644
--- a/converter/pgm/st4topgm.c
+++ b/converter/pgm/st4topgm.c
@@ -69,11 +69,11 @@ writeRaster(FILE *       const ifP,
         unsigned int col;
 
         for (col = 0; col < st4Width; ++col) {
-            char c;
+            unsigned char c;
 
-            pm_readchar(ifP, &c);
+            pm_readcharu(ifP, &c);
 
-            tuplerow[col][0] = (unsigned char)c;
+            tuplerow[col][0] = c;
         }
         pnm_writepamrow(pamP, tuplerow);
     }