diff --git a/libguile/ports.c b/libguile/ports.c
index b754e1bae..a59c8d831 100644
--- a/libguile/ports.c
+++ b/libguile/ports.c
@@ -1555,7 +1555,7 @@ scm_c_read_bytes_unlocked (SCM port, SCM dst, size_t start, size_t count)
    read buffer.  Used by an application when it wants to read into a
    memory chunk that's not owned by Guile's GC.  */
 size_t
-scm_c_read_unlocked (SCM port, void *buffer, size_t size)
+scm_c_read (SCM port, void *buffer, size_t size)
 #define FUNC_NAME "scm_c_read"
 {
   size_t copied = 0;
@@ -1570,15 +1570,20 @@ scm_c_read_unlocked (SCM port, void *buffer, size_t size)
 
   if (pt->rw_random)
     {
-      if (pt->rw_active == SCM_PORT_WRITE)
-        scm_flush_unlocked (port);
+      int needs_flush;
+      scm_i_pthread_mutex_lock (pt->lock);
+      needs_flush = pt->rw_active == SCM_PORT_WRITE;
       pt->rw_active = SCM_PORT_READ;
+      scm_i_pthread_mutex_unlock (pt->lock);
+
+      if (needs_flush)
+        scm_flush (port);
     }
 
   while (copied < size)
     {
       size_t count;
-      read_buf = scm_fill_input_unlocked (port);
+      read_buf = scm_fill_input (port);
       count = scm_port_buffer_take (read_buf, dst + copied, size - copied);
       copied += count;
       if (count == 0)
@@ -1607,20 +1612,6 @@ scm_c_read_bytes (SCM port, SCM dst, size_t start, size_t count)
   return ret;
 }
 
-size_t
-scm_c_read (SCM port, void *buffer, size_t size)
-{
-  scm_i_pthread_mutex_t *lock;
-  size_t ret;
-
-  scm_c_lock_port (port, &lock);
-  ret = scm_c_read_unlocked (port, buffer, size);
-  if (lock)
-    scm_i_pthread_mutex_unlock (lock);
-
-  return ret;
-}
-
 /* Update the line and column number of PORT after consumption of C.  */
 static inline void
 update_port_lf (scm_t_wchar c, SCM port)
diff --git a/libguile/ports.h b/libguile/ports.h
index 2cd6f8be7..2b05a229f 100644
--- a/libguile/ports.h
+++ b/libguile/ports.h
@@ -310,7 +310,6 @@ SCM_INLINE int scm_c_try_lock_port (SCM port, scm_i_pthread_mutex_t **lock);
 SCM_API int scm_get_byte_or_eof (SCM port);
 SCM_API int scm_peek_byte_or_eof (SCM port);
 SCM_API size_t scm_c_read (SCM port, void *buffer, size_t size);
-SCM_API size_t scm_c_read_unlocked (SCM port, void *buffer, size_t size);
 SCM_API size_t scm_c_read_bytes (SCM port, SCM dst, size_t start, size_t count);
 SCM_API scm_t_wchar scm_getc (SCM port);
 SCM_API scm_t_wchar scm_getc_unlocked (SCM port);
diff --git a/libguile/read.c b/libguile/read.c
index 144e39dc5..75f042377 100644
--- a/libguile/read.c
+++ b/libguile/read.c
@@ -2100,7 +2100,7 @@ scm_i_scan_for_encoding (SCM port)
       if (SCM_FPORTP (port) && !SCM_FDES_RANDOM_P (SCM_FPORT_FDES (port)))
         return NULL;
 
-      bytes_read = scm_c_read_unlocked (port, header, SCM_ENCODING_SEARCH_SIZE);
+      bytes_read = scm_c_read (port, header, SCM_ENCODING_SEARCH_SIZE);
       header[bytes_read] = '\0';
       scm_seek (port, scm_from_int (0), scm_from_int (SEEK_SET));
     }