diff --git a/ChangeLog.adoc b/ChangeLog.adoc
index 00d863cbb..68f6f6be3 100644
--- a/ChangeLog.adoc
+++ b/ChangeLog.adoc
@@ -27,6 +27,7 @@ New features::
 Bug fixes::
 
   * core: fix display glitch in command errors when a wide char is set in option weechat.look.command_chars (issue #1871)
+  * api: readjust string size in function string_dyn_free when string is not freed
   * irc: fix join of channels in "autojoin" server option on first connection to server if auto reconnection is performed (issue #1873)
   * typing: fix crash when pointer buffer is not received in callback for signal "input_text_changed" (issue #1869)
 
diff --git a/src/core/wee-eval.c b/src/core/wee-eval.c
index 01dce0999..d80be2df9 100644
--- a/src/core/wee-eval.c
+++ b/src/core/wee-eval.c
@@ -334,10 +334,7 @@ eval_string_range_chars (const char *range)
 
 end:
     if (string)
-    {
-        result = *string;
-        string_dyn_free (string, 0);
-    }
+        result = string_dyn_free (string, 0);
 
     return (result) ? result : strdup ("");
 }
diff --git a/src/core/wee-string.c b/src/core/wee-string.c
index 346cfc265..368cee7d2 100644
--- a/src/core/wee-string.c
+++ b/src/core/wee-string.c
@@ -4409,7 +4409,6 @@ string_dyn_copy (char **string, const char *new_string)
         if (!string_realloc)
             return 0;
         ptr_string_dyn->string = string_realloc;
-        *string = string_realloc;
         ptr_string_dyn->size_alloc = new_size_alloc;
     }
 
@@ -4475,7 +4474,6 @@ string_dyn_concat (char **string, const char *add, int bytes)
             return 0;
         }
         ptr_string_dyn->string = string_realloc;
-        *string = string_realloc;
         ptr_string_dyn->size_alloc = new_size_alloc;
     }
 
@@ -4496,8 +4494,11 @@ string_dyn_concat (char **string, const char *add, int bytes)
  * string_dyn_alloc or a string pointer modified by string_dyn_concat.
  *
  * If free_string == 1, the string itself is freed in the structure.
- * Otherwise the pointer (*string) remains valid after this call, and
- * the caller must manually free the string with a call to free().
+ *
+ * If free_string == 0, the pointer (*string) remains valid after this call,
+ * and the caller must manually free the string with a call to free().
+ * Be careful, the pointer in *string may change after this call because
+ * the string can be reallocated to its exact size.
  *
  * Returns the pointer to the string if "free_string" is 0 (string
  * pointer is still valid), or NULL if "free_string" is 1 (string
@@ -4508,7 +4509,7 @@ char *
 string_dyn_free (char **string, int free_string)
 {
     struct t_string_dyn *ptr_string_dyn;
-    char *ptr_string;
+    char *ptr_string, *string_realloc;
 
     if (!string || !*string)
         return NULL;
@@ -4522,6 +4523,14 @@ string_dyn_free (char **string, int free_string)
     }
     else
     {
+        /* if needed, realloc the string to its exact size */
+        if (ptr_string_dyn->size_alloc > ptr_string_dyn->size)
+        {
+            string_realloc = realloc (ptr_string_dyn->string,
+                                      ptr_string_dyn->size);
+            if (string_realloc)
+                ptr_string_dyn->string = string_realloc;
+        }
         ptr_string = ptr_string_dyn->string;
     }
 
diff --git a/src/plugins/buflist/buflist-bar-item.c b/src/plugins/buflist/buflist-bar-item.c
index 1c7abf3c9..d7dcc0868 100644
--- a/src/plugins/buflist/buflist-bar-item.c
+++ b/src/plugins/buflist/buflist-bar-item.c
@@ -574,8 +574,7 @@ buflist_bar_item_buflist_cb (const void *pointer, void *data,
                                                    -1);
                     }
                 }
-                str_hotlist = *hotlist;
-                weechat_string_dyn_free (hotlist, 0);
+                str_hotlist = weechat_string_dyn_free (hotlist, 0);
             }
         }
         weechat_hashtable_set (
@@ -655,15 +654,15 @@ buflist_bar_item_buflist_cb (const void *pointer, void *data,
         line_number++;
     }
 
-    str_buflist = *buflist;
+    str_buflist = weechat_string_dyn_free (buflist, 0);
 
     goto end;
 
 error:
+    weechat_string_dyn_free (buflist, 1);
     str_buflist = NULL;
 
 end:
-    weechat_string_dyn_free (buflist, 0);
     weechat_arraylist_free (buffers);
 
     if ((line_number_current_buffer != old_line_number_current_buffer[item_index])
diff --git a/src/plugins/irc/irc-join.c b/src/plugins/irc/irc-join.c
index 82f8566b2..609c2b50c 100644
--- a/src/plugins/irc/irc-join.c
+++ b/src/plugins/irc/irc-join.c
@@ -372,10 +372,7 @@ irc_join_build_string (struct t_arraylist *arraylist)
 
 end:
     if (channels)
-    {
-        result = *channels;
-        weechat_string_dyn_free (channels, 0);
-    }
+        result = weechat_string_dyn_free (channels, 0);
     if (keys)
         weechat_string_dyn_free (keys, 1);