diff --git a/lib/libshare/nfs.c b/lib/libshare/nfs.c
index 118ad7ef2..3962c8745 100644
--- a/lib/libshare/nfs.c
+++ b/lib/libshare/nfs.c
@@ -97,7 +97,7 @@ nfs_init_tmpfile(const char *prefix, const char *mdir, struct tmpfile *tmpf)
 	}
 
 	strlcpy(tmpf->name, prefix, sizeof (tmpf->name));
-	strlcat(tmpf->name, ".XXXXXXXX", sizeof (tmpf->name) - strlen(prefix));
+	strlcat(tmpf->name, ".XXXXXXXX", sizeof (tmpf->name));
 
 	int fd = mkostemp(tmpf->name, O_CLOEXEC);
 	if (fd == -1) {
diff --git a/lib/libzfs/libzfs_sendrecv.c b/lib/libzfs/libzfs_sendrecv.c
index 1d2ad1944..66a22e333 100644
--- a/lib/libzfs/libzfs_sendrecv.c
+++ b/lib/libzfs/libzfs_sendrecv.c
@@ -4590,7 +4590,7 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 			    B_FALSE, destsnap) == 0) {
 				*strchr(destsnap, '@') = '\0';
 				(void) strlcat(destsnap, suffix,
-				    sizeof (destsnap) - strlen(destsnap));
+				    sizeof (destsnap));
 			}
 		}
 	} else {
@@ -4626,7 +4626,7 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 			    B_FALSE, destsnap) == 0) {
 				*strchr(destsnap, '@') = '\0';
 				(void) strlcat(destsnap, snap,
-				    sizeof (destsnap) - strlen(destsnap));
+				    sizeof (destsnap));
 			}
 		}
 	}
diff --git a/module/zfs/dmu_send.c b/module/zfs/dmu_send.c
index 33beb04b1..f86a0a5b1 100644
--- a/module/zfs/dmu_send.c
+++ b/module/zfs/dmu_send.c
@@ -3029,8 +3029,7 @@ dmu_send_estimate_fast(dsl_dataset_t *origds, dsl_dataset_t *fromds,
 
 		dsl_dataset_name(origds, dsname);
 		(void) strcat(dsname, "/");
-		(void) strlcat(dsname, recv_clone_name,
-		    sizeof (dsname) - strlen(dsname));
+		(void) strlcat(dsname, recv_clone_name, sizeof (dsname));
 
 		err = dsl_dataset_hold(origds->ds_dir->dd_pool,
 		    dsname, FTAG, &ds);