diff --git a/programs/test/selftest.c b/programs/test/selftest.c
index d312755..88c0188 100644
--- a/programs/test/selftest.c
+++ b/programs/test/selftest.c
@@ -74,7 +74,7 @@
     void *buffer1 = mbedtls_calloc(1, 1);
     void *buffer2 = mbedtls_calloc(1, 1);
     unsigned int buf_size = 256;
-    unsigned char *buffer3 = mbedtls_calloc(buf_size, sizeof(unsigned char));
+    unsigned char *buffer3 = mbedtls_calloc(buf_size, 1);
 
     if (empty1 == NULL && empty2 == NULL) {
         if (verbose) {