diff --git a/src/wasm-sample/shape.c b/src/wasm-sample/shape.c
index a95c80a44..480701771 100644
--- a/src/wasm-sample/shape.c
+++ b/src/wasm-sample/shape.c
@@ -2,6 +2,8 @@
 
 #include <hb-wasm-api.h>
 
+void free (void*);
+
 void debugprint1 (char *s, int32_t);
 void debugprint2 (char *s, int32_t, int32_t);
 
@@ -14,6 +16,8 @@ shape (font_t font, buffer_t buffer)
 
   debugprint1 ("cmap length", blob.length);
 
+  free (blob.data);
+
   buffer_contents_t contents = buffer_copy_contents (buffer);
 
   debugprint1 ("buffer length", contents.length);