diff --git a/docs/parsers/asciitable.md b/docs/parsers/asciitable.md
index 10238221..de06fcc0 100644
--- a/docs/parsers/asciitable.md
+++ b/docs/parsers/asciitable.md
@@ -45,6 +45,9 @@ For example:
 
     etc...
 
+    Headers (keys) are converted to snake-case. All values are returned as
+    strings, except empty strings, which are converted to None/null.
+
 Usage (cli):
 
     $ cat table.txt | jc --asciitable
diff --git a/docs/parsers/asciitable_m.md b/docs/parsers/asciitable_m.md
index 2e72cfca..90ae4774 100644
--- a/docs/parsers/asciitable_m.md
+++ b/docs/parsers/asciitable_m.md
@@ -26,7 +26,8 @@ Cells with multiple lines within rows will be joined with a newline
 character ('\n').
 
 Headers (keys) are converted to snake-case and newlines between multi-line
-headers are joined with an underscore. All values are returned as strings.
+headers are joined with an underscore. All values are returned as strings,
+except empty strings, which are converted to None/null.
 
 Usage (cli):
 
diff --git a/jc/parsers/asciitable.py b/jc/parsers/asciitable.py
index 281f7578..c45805e0 100644
--- a/jc/parsers/asciitable.py
+++ b/jc/parsers/asciitable.py
@@ -40,6 +40,9 @@ For example:
 
     etc...
 
+    Headers (keys) are converted to snake-case. All values are returned as
+    strings, except empty strings, which are converted to None/null.
+
 Usage (cli):
 
     $ cat table.txt | jc --asciitable
diff --git a/jc/parsers/asciitable_m.py b/jc/parsers/asciitable_m.py
index 63f59a27..c8907868 100644
--- a/jc/parsers/asciitable_m.py
+++ b/jc/parsers/asciitable_m.py
@@ -21,7 +21,8 @@ Cells with multiple lines within rows will be joined with a newline
 character ('\n').
 
 Headers (keys) are converted to snake-case and newlines between multi-line
-headers are joined with an underscore. All values are returned as strings.
+headers are joined with an underscore. All values are returned as strings,
+except empty strings, which are converted to None/null.
 
 Usage (cli):