diff --git a/arrays_strings/replace_char/replace_char_challenge.ipynb b/arrays_strings/replace_char/replace_char_challenge.ipynb
index acc7df2..77c60ab 100644
--- a/arrays_strings/replace_char/replace_char_challenge.ipynb
+++ b/arrays_strings/replace_char/replace_char_challenge.ipynb
@@ -18,7 +18,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Problem: Given a string, replace all spaces with '%20', in-place\n",
+    "## Problem: Given a string (a list of characters), replace all spaces with '%20', in-place\n",
     "\n",
     "* [Constraints](#Constraints)\n",
     "* [Test Cases](#Test-Cases)\n",
diff --git a/arrays_strings/replace_char/replace_char_solution.ipynb b/arrays_strings/replace_char/replace_char_solution.ipynb
index 4feacae..7e6ca7c 100644
--- a/arrays_strings/replace_char/replace_char_solution.ipynb
+++ b/arrays_strings/replace_char/replace_char_solution.ipynb
@@ -18,7 +18,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Problem: Given a string, replace in-place all spaces with '%20'\n",
+    "## Problem: Given a string (a list of characters), replace in-place all spaces with '%20'\n",
     "\n",
     "* [Constraints](#Constraints)\n",
     "* [Test Cases](#Test-Cases)\n",
@@ -42,7 +42,7 @@
     "    * Note: Unicode strings could require special handling depending on your language\n",
     "* Is there enough space in the data structure for this operation?\n",
     "    * Yes\n",
-    "* Since Python strings are immutable and we are asked to do this in-place, can I use a bytearray or a list instead?\n",
+    "* Since Python strings are immutable and we are asked to do this in-place, can I use a list or a bytearray instead?\n",
     "    * Yes"
    ]
   },