diff --git a/Write_An_Assembler.ipynb b/Write_An_Assembler.ipynb
index c61432d..113a11b 100644
--- a/Write_An_Assembler.ipynb
+++ b/Write_An_Assembler.ipynb
@@ -922,7 +922,7 @@
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "Build a squence database\n",
+      "Build a sequence database\n",
       "------------------------\n",
       "Since we get the paths that seems covering the whole genome, we can use the paths to construct draft contigs. In order to do that, we need to get the fragment sequences."
      ]
diff --git a/Write_An_Assembler.py b/Write_An_Assembler.py
index 05d2457..01154b9 100644
--- a/Write_An_Assembler.py
+++ b/Write_An_Assembler.py
@@ -655,7 +655,7 @@ def find_path( q_name_end, frag_used = set() ):
 
 # <markdowncell>
 
-# Build a squence database
+# Build a sequence database
 # ------------------------
 # Since we get the paths that seems covering the whole genome, we can use the paths to construct draft contigs. In order to do that, we need to get the fragment sequences.