diff --git a/libctf/ChangeLog b/libctf/ChangeLog
index cca704a4ec2..39cf47d0b36 100644
--- a/libctf/ChangeLog
+++ b/libctf/ChangeLog
@@ -1,3 +1,13 @@
+2020-07-22  Nick Alcock  <nick.alcock@oracle.com>
+
+	* ctf-impl.h (ctf_dtdef_t) <dtu_argv>: Fix type.
+	* ctf-create.c (ctf_add_function): Check for unimplemented type
+	and populate at the same time.  Populate one-by-one, not via
+	memcpy.
+	(ctf_serialize): Remove unnecessary cast.
+	* ctf-types.c (ctf_func_type_info): Likewise.
+	(ctf_func_type_args): Likewise.  Fix comment typo.
+
 2020-07-22  Nick Alcock  <nick.alcock@oracle.com>
 
 	* ctf-create.c (ctf_add_reftype): Support refs to type zero.
diff --git a/libctf/ctf-create.c b/libctf/ctf-create.c
index 67a3f199a96..f91da6ea159 100644
--- a/libctf/ctf-create.c
+++ b/libctf/ctf-create.c
@@ -448,7 +448,7 @@ ctf_serialize (ctf_file_t *fp)
 	    uint32_t argc;
 
 	    for (argc = 0; argc < vlen; argc++)
-	      *argv++ = (uint32_t) dtd->dtd_u.dtu_argv[argc];
+	      *argv++ = dtd->dtd_u.dtu_argv[argc];
 
 	    if (vlen & 1)
 	      *argv++ = 0;	/* Pad to 4-byte boundary.  */
@@ -1052,7 +1052,7 @@ ctf_add_function (ctf_file_t *fp, uint32_t flag,
   ctf_dtdef_t *dtd;
   ctf_id_t type;
   uint32_t vlen;
-  ctf_id_t *vdat = NULL;
+  uint32_t *vdat = NULL;
   ctf_file_t *tmp = fp;
   size_t i;
 
@@ -1068,19 +1068,23 @@ ctf_add_function (ctf_file_t *fp, uint32_t flag,
       && ctf_lookup_by_id (&tmp, ctc->ctc_return) == NULL)
     return CTF_ERR;		/* errno is set for us.  */
 
-  for (i = 0; i < ctc->ctc_argc; i++)
-    {
-      tmp = fp;
-      if (argv[i] != 0 && ctf_lookup_by_id (&tmp, argv[i]) == NULL)
-	return CTF_ERR;		/* errno is set for us.  */
-    }
-
   if (vlen > CTF_MAX_VLEN)
     return (ctf_set_errno (fp, EOVERFLOW));
 
   if (vlen != 0 && (vdat = malloc (sizeof (ctf_id_t) * vlen)) == NULL)
     return (ctf_set_errno (fp, EAGAIN));
 
+  for (i = 0; i < ctc->ctc_argc; i++)
+    {
+      tmp = fp;
+      if (argv[i] != 0 && ctf_lookup_by_id (&tmp, argv[i]) == NULL)
+	{
+	  free (vdat);
+	  return CTF_ERR;	   /* errno is set for us.  */
+	}
+      vdat[i] = (uint32_t) argv[i];
+    }
+
   if ((type = ctf_add_generic (fp, flag, NULL, CTF_K_FUNCTION,
 			       &dtd)) == CTF_ERR)
     {
@@ -1091,7 +1095,6 @@ ctf_add_function (ctf_file_t *fp, uint32_t flag,
   dtd->dtd_data.ctt_info = CTF_TYPE_INFO (CTF_K_FUNCTION, flag, vlen);
   dtd->dtd_data.ctt_type = (uint32_t) ctc->ctc_return;
 
-  memcpy (vdat, argv, sizeof (ctf_id_t) * ctc->ctc_argc);
   if (ctc->ctc_flags & CTF_FUNC_VARARG)
     vdat[vlen - 1] = 0;		   /* Add trailing zero to indicate varargs.  */
   dtd->dtd_u.dtu_argv = vdat;
diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
index b20a4f05a80..fdd48f0d331 100644
--- a/libctf/ctf-impl.h
+++ b/libctf/ctf-impl.h
@@ -172,7 +172,7 @@ typedef struct ctf_dtdef
     ctf_list_t dtu_members;	/* struct, union, or enum */
     ctf_arinfo_t dtu_arr;	/* array */
     ctf_encoding_t dtu_enc;	/* integer or float */
-    ctf_id_t *dtu_argv;		/* function */
+    uint32_t *dtu_argv;		/* function */
     ctf_slice_t dtu_slice;	/* slice */
   } dtd_u;
 } ctf_dtdef_t;
diff --git a/libctf/ctf-types.c b/libctf/ctf-types.c
index cd910434ea4..35253cb3cbc 100644
--- a/libctf/ctf-types.c
+++ b/libctf/ctf-types.c
@@ -1163,7 +1163,7 @@ ctf_func_type_info (ctf_file_t *fp, ctf_id_t type, ctf_funcinfo_t *fip)
   if ((dtd = ctf_dynamic_type (fp, type)) == NULL)
     args = (uint32_t *) ((uintptr_t) tp + increment);
   else
-    args = (uint32_t *) dtd->dtd_u.dtu_argv;
+    args = dtd->dtd_u.dtu_argv;
 
   if (fip->ctc_argc != 0 && args[fip->ctc_argc - 1] == 0)
     {
@@ -1174,7 +1174,7 @@ ctf_func_type_info (ctf_file_t *fp, ctf_id_t type, ctf_funcinfo_t *fip)
   return 0;
 }
 
-/* Given a type ID relating to a function type,, return the arguments for the
+/* Given a type ID relating to a function type, return the arguments for the
    function.  */
 
 int
@@ -1200,7 +1200,7 @@ ctf_func_type_args (ctf_file_t *fp, ctf_id_t type, uint32_t argc, ctf_id_t *argv
   if ((dtd = ctf_dynamic_type (fp, type)) == NULL)
     args = (uint32_t *) ((uintptr_t) tp + increment);
   else
-    args = (uint32_t *) dtd->dtd_u.dtu_argv;
+    args = dtd->dtd_u.dtu_argv;
 
   for (argc = MIN (argc, f.ctc_argc); argc != 0; argc--)
     *argv++ = *args++;