diff --git a/COMPAT.md b/COMPAT.md
index 5b03e76e3..1e0def3aa 100644
--- a/COMPAT.md
+++ b/COMPAT.md
@@ -107,7 +107,7 @@ This document describes the SQLite compatibility status of Limbo:
 | substr(X,Y,Z)                | No     |         |
 | substr(X,Y)                  | No     |         |
 | substring(X,Y,Z)             | Yes    |         |
-| substring(X,Y)               | No     |         |
+| substring(X,Y)               | Yes    |         |
 | total_changes()              | No     |         |
 | trim(X)                      | Yes    |         |
 | trim(X,Y)                    | Yes    |         |
diff --git a/core/translate/expr.rs b/core/translate/expr.rs
index 1fb7e1de1..dc9396396 100644
--- a/core/translate/expr.rs
+++ b/core/translate/expr.rs
@@ -304,9 +304,9 @@ pub fn translate_expr(
                         }
                         ScalarFunc::Substring => {
                             let args = if let Some(args) = args {
-                                if args.len() != 3  {
+                                if !(args.len() == 2 || args.len() == 3)  {
                                     crate::bail_parse_error!(
-                                        "{} function with not exactly 3 arguments",
+                                        "{} function with wrong number of arguments",
                                         srf.to_string()
                                     )
                                 }
@@ -324,7 +324,9 @@ pub fn translate_expr(
 
                             translate_expr(program, select, &args[0], str_reg, cursor_hint)?;
                             translate_expr(program, select, &args[1], start_reg, cursor_hint)?;
-                            translate_expr(program, select, &args[2], length_reg, cursor_hint)?;
+                            if args.len() == 3 {
+                                translate_expr(program, select, &args[2], length_reg, cursor_hint)?;
+                            }
 
                             program.emit_insn(Insn::Function {
                                 start_reg: str_reg,
diff --git a/core/vdbe/mod.rs b/core/vdbe/mod.rs
index 0031b4169..c1580ff11 100644
--- a/core/vdbe/mod.rs
+++ b/core/vdbe/mod.rs
@@ -1650,20 +1650,31 @@ fn exec_minmax<'a>(
 }
 
 fn exec_substring(str_value: &OwnedValue, start_value: &OwnedValue, length_value: &OwnedValue) -> OwnedValue {
-    match (str_value, start_value, length_value) {
-        (OwnedValue::Text(str), OwnedValue::Integer(start), OwnedValue::Integer(length)) => {
-            let start = *start as usize;
-            if (start as usize) > str.len() {
-                OwnedValue::Text(Rc::new("".to_string()))
-            } else {
-                let length = *length as usize;
-                let start_idx = start - 1;
-                let end = start_idx + length;
-                let substring = &str[start_idx..end.min(str.len())];
-                OwnedValue::Text(Rc::new(substring.to_string()))
-            }
+    if let (OwnedValue::Text(str), OwnedValue::Integer(start), OwnedValue::Integer(length)) = (str_value, start_value, length_value) {
+        let start = *start as usize;
+        if start > str.len() {
+            return OwnedValue::Text(Rc::new("".to_string()));
         }
-        _ => OwnedValue::Null,
+
+        let start_idx = start - 1;
+        let str_len = str.len();
+        let end = if *length != -1 { start_idx + *length as usize } else { str_len };
+        let substring = &str[start_idx..end.min(str_len)];
+
+        OwnedValue::Text(Rc::new(substring.to_string()))
+    } else if let (OwnedValue::Text(str), OwnedValue::Integer(start)) = (str_value, start_value) {
+        let start = *start as usize;
+        if start > str.len() {
+            return OwnedValue::Text(Rc::new("".to_string()));
+        }
+
+        let start_idx = start - 1;
+        let str_len = str.len();
+        let substring = &str[start_idx..str_len];
+
+        OwnedValue::Text(Rc::new(substring.to_string()))
+    } else {
+        OwnedValue::Null
     }
 }
 
@@ -2190,5 +2201,17 @@ mod tests {
         let length_value = OwnedValue::Integer(3);
         let expected_val = OwnedValue::Text(Rc::new(String::from("")));
         assert_eq!(exec_substring(&str_value, &start_value, &length_value), expected_val);
+
+        let str_value = OwnedValue::Text(Rc::new("limbo".to_string()));
+        let start_value = OwnedValue::Integer(3);
+        let length_value = OwnedValue::Null;
+        let expected_val = OwnedValue::Text(Rc::new(String::from("mbo")));
+        assert_eq!(exec_substring(&str_value, &start_value, &length_value), expected_val);
+
+        let str_value = OwnedValue::Text(Rc::new("limbo".to_string()));
+        let start_value = OwnedValue::Integer(10);
+        let length_value = OwnedValue::Null;
+        let expected_val = OwnedValue::Text(Rc::new(String::from("")));
+
     }
 }
diff --git a/testing/scalar-functions.test b/testing/scalar-functions.test
index 5f3264564..b29685118 100755
--- a/testing/scalar-functions.test
+++ b/testing/scalar-functions.test
@@ -239,18 +239,26 @@ do_execsql_test max-null {
   select max(null,null)
 } {}
 
-do_execsql_test substr {
+do_execsql_test substr-3-args {
   SELECT substr('limbo', 1, 3);
 } {lim}
 
-do_execsql_test substr-exceed-length {
+do_execsql_test substr-3-args-exceed-length {
   SELECT substr('limbo', 1, 10);
 } {limbo}
 
-do_execsql_test substr-start-exceed-length {
+do_execsql_test substr-3-args-start-exceed-length {
   SELECT substr('limbo', 10, 3);
 } {}
 
+do_execsql_test substr-2-args {
+  SELECT substr('limbo', 3);
+} {mbo}
+
+do_execsql_test substr-2-args-exceed-length {
+  SELECT substr('limbo', 10);
+} {}
+
 do_execsql_test date-current-date {
   SELECT length(date('now')) = 10;
 } {1}