diff --git a/nimterop/exprparser.nim b/nimterop/exprparser.nim
index 0fea184..0d2099a 100644
--- a/nimterop/exprparser.nim
+++ b/nimterop/exprparser.nim
@@ -140,8 +140,6 @@ proc getIntNode(number, suffix: string): PNode {.inline.} =
   var
     val: BiggestInt
     flags: TNodeFlags
-  # I realize these regex are wasteful on performance, but
-  # couldn't come up with a better idea.
   if number.startsWith("0X") or number.startsWith("0x"):
     val = parseHexInt(number)
     flags = {nfBase16}
@@ -203,6 +201,9 @@ proc processNumberLiteral(gState: State, node: TSNode): PNode =
   if number.startsWith("-"):
     number = number[1 ..< number.len]
     prefix = "-"
+  if number.len > 1 and number[0] == '0' and number[1] notin ['x', 'X']:
+    # Octal 0123
+    number = "0o" & number[1 .. ^1]
   if tripleEndings.any(proc (s: string): bool = number.endsWith(s)):
     suffix = number[^3 .. ^1]
     number = number[0 ..< ^3]
diff --git a/tests/include/tast2.h b/tests/include/tast2.h
index 019f7c4..6f569d5 100644
--- a/tests/include/tast2.h
+++ b/tests/include/tast2.h
@@ -7,6 +7,7 @@ extern "C" {
 #define C 0x10
 #define D "hello"
 #define E 'c'
+#define F 01234
 
 #define UEXPR (1234u << 1)
 #define ULEXPR (1234ul << 2)
diff --git a/tests/tast2.nim b/tests/tast2.nim
index fd0175a..124c4e4 100644
--- a/tests/tast2.nim
+++ b/tests/tast2.nim
@@ -110,6 +110,7 @@ assert B == 1.0
 assert C == 0x10
 assert D == "hello"
 assert E == 'c'
+assert F == 0o1234
 
 assert not defined(NOTSUPPORTEDSTR)