diff --git a/include/qemu/iov.h b/include/qemu/iov.h
index 44f9db5cee..9535673c13 100644
--- a/include/qemu/iov.h
+++ b/include/qemu/iov.h
@@ -31,7 +31,7 @@ size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
  * only part of data will be copied, up to the end of the iovec.
  * Number of bytes actually copied will be returned, which is
  *  min(bytes, iov_size(iov)-offset)
- * `Offset' must point to the inside of iovec.
+ * Returns 0 when `offset' points to the outside of iovec.
  */
 size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt,
                          size_t offset, const void *buf, size_t bytes);
@@ -67,11 +67,12 @@ iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
 /**
  * Set data bytes pointed out by iovec `iov' of size `iov_cnt' elements,
  * starting at byte offset `start', to value `fillc', repeating it
- * `bytes' number of times.  `Offset' must point to the inside of iovec.
+ * `bytes' number of times.
  * If `bytes' is large enough, only last bytes portion of iovec,
  * up to the end of it, will be filled with the specified value.
  * Function return actual number of bytes processed, which is
  * min(size, iov_size(iov) - offset).
+ * Returns 0 when `offset' points to the outside of iovec.
  */
 size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
                   size_t offset, int fillc, size_t bytes);
diff --git a/util/iov.c b/util/iov.c
index 7777116123..f8536f0474 100644
--- a/util/iov.c
+++ b/util/iov.c
@@ -37,7 +37,6 @@ size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt,
             offset -= iov[i].iov_len;
         }
     }
-    assert(offset == 0);
     return done;
 }
 
@@ -56,7 +55,6 @@ size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt,
             offset -= iov[i].iov_len;
         }
     }
-    assert(offset == 0);
     return done;
 }
 
@@ -75,7 +73,6 @@ size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
             offset -= iov[i].iov_len;
         }
     }
-    assert(offset == 0);
     return done;
 }
 
@@ -277,7 +274,6 @@ unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
         bytes -= len;
         offset = 0;
     }
-    assert(offset == 0);
     return j;
 }
 
@@ -348,7 +344,6 @@ size_t qemu_iovec_concat_iov(QEMUIOVector *dst,
             soffset -= src_iov[i].iov_len;
         }
     }
-    assert(soffset == 0); /* offset beyond end of src */
 
     return done;
 }