diff --git a/src/strace/parser/mod.rs b/src/strace/parser/mod.rs
index 52f140e..5a9cc6f 100644
--- a/src/strace/parser/mod.rs
+++ b/src/strace/parser/mod.rs
@@ -269,15 +269,15 @@ mod tests {
                                 complement: true,
                                 values: vec![
                                     Expression::Integer(
-                                        IntegerExpression { 
+                                        IntegerExpression {
                                             value: IntegerExpressionValue::NamedConst("RTMIN".to_owned()), 
-                                            metadata: None 
+                                            metadata: None
                                         }
                                     ),
                                     Expression::Integer(
-                                        IntegerExpression { 
+                                        IntegerExpression {
                                             value: IntegerExpressionValue::NamedConst("RT_1".to_owned()), 
-                                            metadata: None 
+                                            metadata: None
                                         }
                                     ),
                                 ]
@@ -336,27 +336,27 @@ mod tests {
                         complement: true,
                         values: vec![
                             Expression::Integer(
-                                IntegerExpression { 
-                                    value: IntegerExpressionValue::NamedConst("KILL".to_owned()), 
-                                    metadata: None 
+                                IntegerExpression {
+                                    value: IntegerExpressionValue::NamedConst("KILL".to_owned()),
+                                    metadata: None
                                 }
                             ),
                             Expression::Integer(
-                                IntegerExpression { 
-                                    value: IntegerExpressionValue::NamedConst("STOP".to_owned()), 
-                                    metadata: None 
+                                IntegerExpression {
+                                    value: IntegerExpressionValue::NamedConst("STOP".to_owned()),
+                                    metadata: None
                                 }
                             ),
                             Expression::Integer(
-                                IntegerExpression { 
-                                    value: IntegerExpressionValue::NamedConst("RTMIN".to_owned()), 
-                                    metadata: None 
+                                IntegerExpression {
+                                    value: IntegerExpressionValue::NamedConst("RTMIN".to_owned()),
+                                    metadata: None
                                 }
                             ),
                             Expression::Integer(
-                                IntegerExpression { 
-                                    value: IntegerExpressionValue::NamedConst("RT_1".to_owned()), 
-                                    metadata: None 
+                                IntegerExpression {
+                                    value: IntegerExpressionValue::NamedConst("RT_1".to_owned()),
+                                    metadata: None
                                 }
                             ),
                         ],
@@ -1331,12 +1331,10 @@ mod tests {
                         }),
                         Expression::Collection {
                             complement: false,
-                            values: vec![
-                                Expression::Integer(IntegerExpression {
-                                    value: IntegerExpressionValue::Literal(3),
-                                    metadata: None,
-                                })
-                            ]
+                            values: vec![Expression::Integer(IntegerExpression {
+                                value: IntegerExpressionValue::Literal(3),
+                                metadata: None,
+                            })]
                         },
                         Expression::Integer(IntegerExpression {
                             value: IntegerExpressionValue::NamedConst("NULL".to_owned()),
diff --git a/src/strace/parser/regex.rs b/src/strace/parser/regex.rs
index 84b893f..88dc157 100644
--- a/src/strace/parser/regex.rs
+++ b/src/strace/parser/regex.rs
@@ -338,19 +338,21 @@ fn parse_argument(caps: &regex::Captures) -> anyhow::Result<Expression> {
             } else {
                 let int_tokens = tokens
                     .into_iter()
-                    .map(|t| {
+                    .map(|t| -> anyhow::Result<_> {
                         if let Some(one_shift) = t.strip_prefix("1<<") {
-                            IntegerExpressionValue::LeftBitShift {
+                            Ok(IntegerExpressionValue::LeftBitShift {
                                 bits: Box::new(IntegerExpressionValue::Literal(1)),
                                 shift: Box::new(IntegerExpressionValue::NamedConst(
                                     one_shift.to_owned(),
                                 )),
-                            }
+                            })
+                        } else if t.starts_with("0") {
+                            Ok(IntegerExpressionValue::Literal(i128::from_str_radix(t, 8)?))
                         } else {
-                            IntegerExpressionValue::NamedConst(t.to_owned())
+                            Ok(IntegerExpressionValue::NamedConst(t.to_owned()))
                         }
                     })
-                    .collect();
+                    .collect::<Result<_, _>>()?;
                 Ok(Expression::Integer(IntegerExpression {
                     value: IntegerExpressionValue::BinaryOr(int_tokens),
                     metadata: None,