diff --git a/src/Makefile.am b/src/Makefile.am
index 70c51d1e0..845c24acd 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -11,7 +11,7 @@ lib_LTLIBRARIES = libharfbuzz.la
 HBCFLAGS =
 HBLIBS =
 HBSOURCES =  \
-	hb-blob.c \
+	hb-blob.cc \
 	hb-blob-private.h \
 	hb-buffer.cc \
 	hb-buffer-private.hh \
diff --git a/src/hb-blob.c b/src/hb-blob.cc
similarity index 99%
rename from src/hb-blob.c
rename to src/hb-blob.cc
index 5419078ef..511455b79 100644
--- a/src/hb-blob.c
+++ b/src/hb-blob.cc
@@ -331,7 +331,7 @@ hb_blob_try_writable (hb_blob_t *blob)
     if (blob->lock_count)
       goto done;
 
-    new_data = malloc (blob->length);
+    new_data = (char *) malloc (blob->length);
     if (new_data) {
       (void) (HB_DEBUG_BLOB &&
 	fprintf (stderr, "%p %s: dupped successfully -> %p\n", blob, __FUNCTION__, blob->data));