diff --git a/Cargo.lock b/Cargo.lock
index 3b8e35ffd..e90229dad 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -864,6 +864,26 @@ name = "ordermap"
 version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "paste"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "paste-impl 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro-hack 0.5.10 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "paste-impl"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "proc-macro-hack 0.5.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "petgraph"
 version = "0.4.13"
@@ -1302,6 +1322,7 @@ dependencies = [
  "num-rational 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "paste 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro-hack 0.5.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "pwd 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2224,6 +2245,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum num_cpus 1.10.1 (registry+https://github.com/rust-lang/crates.io-index)" = "bcef43580c035376c0705c42792c294b66974abbfd2789b511784023f71f3273"
 "checksum opaque-debug 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "2839e79665f131bdb5782e51f2c6c9599c133c6098982a54c794358bf432529c"
 "checksum ordermap 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "a86ed3f5f244b372d6b1a00b72ef7f8876d0bc6a78a4c9985c53614041512063"
+"checksum paste 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "423a519e1c6e828f1e73b720f9d9ed2fa643dce8a7737fb43235ce0b41eeaa49"
+"checksum paste-impl 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "4214c9e912ef61bf42b81ba9a47e8aad1b2ffaf739ab162bf96d1e011f54e6c5"
 "checksum petgraph 0.4.13 (registry+https://github.com/rust-lang/crates.io-index)" = "9c3659d1ee90221741f65dd128d9998311b0e40c5d3c23a62445938214abce4f"
 "checksum phf_generator 0.7.24 (registry+https://github.com/rust-lang/crates.io-index)" = "09364cc93c159b8b06b1f4dd8a4398984503483891b0c26b867cf431fb132662"
 "checksum phf_shared 0.7.24 (registry+https://github.com/rust-lang/crates.io-index)" = "234f71a15de2288bcb7e3b6515828d22af7ec8598ee6d24c3b526fa0a80b67a0"
diff --git a/tests/snippets/stdlib_struct.py b/tests/snippets/stdlib_struct.py
index e3153882e..e7be196c9 100644
--- a/tests/snippets/stdlib_struct.py
+++ b/tests/snippets/stdlib_struct.py
@@ -38,3 +38,6 @@ with assert_raises(Exception):
   data = struct.pack('B2B', 65, 66)
 
 data = struct.pack('B1B', 65, 66)
+
+with assert_raises(Exception):
+  struct.pack('<IH', "14", 12)
diff --git a/vm/Cargo.toml b/vm/Cargo.toml
index 4eca99013..ec1a92df7 100644
--- a/vm/Cargo.toml
+++ b/vm/Cargo.toml
@@ -65,6 +65,7 @@ nix = "0.15.0"
 wtf8 = "0.0.3"
 arr_macro = "0.1.2"
 csv = "1.1.1"
+paste = "0.1"
 
 flame = { version = "0.2", optional = true }
 flamer = { version = "0.3", optional = true }
diff --git a/vm/src/stdlib/pystruct.rs b/vm/src/stdlib/pystruct.rs
index 263c1e0cd..f7d17a53a 100644
--- a/vm/src/stdlib/pystruct.rs
+++ b/vm/src/stdlib/pystruct.rs
@@ -13,12 +13,10 @@ use std::io::{Cursor, Read, Write};
 use std::iter::Peekable;
 
 use byteorder::{ReadBytesExt, WriteBytesExt};
-use num_bigint::BigInt;
-use num_traits::ToPrimitive;
 
 use crate::function::PyFuncArgs;
-use crate::obj::{objbool, objbytes, objfloat, objint, objstr, objtype};
-use crate::pyobject::{PyObjectRef, PyResult};
+use crate::obj::{objbytes, objstr, objtype};
+use crate::pyobject::{PyObjectRef, PyResult, TryFromObject};
 use crate::VirtualMachine;
 
 #[derive(Debug)]
@@ -130,144 +128,54 @@ fn is_supported_format_character(c: char) -> bool {
     }
 }
 
-fn get_int(vm: &VirtualMachine, arg: &PyObjectRef) -> PyResult<BigInt> {
-    objint::to_int(vm, arg, &BigInt::from(10))
+macro_rules! make_pack_no_endianess {
+    ($T:ty) => {
+        paste::item! {
+            fn [<pack_ $T>](vm: &VirtualMachine, arg: &PyObjectRef, data: &mut dyn Write) -> PyResult<()> {
+                let v = $T::try_from_object(vm, arg.clone())?;
+                data.[<write_$T>](v).unwrap();
+                Ok(())
+            }
+        }
+    };
 }
 
-fn pack_i8(vm: &VirtualMachine, arg: &PyObjectRef, data: &mut dyn Write) -> PyResult<()> {
-    let v = get_int(vm, arg)?.to_i8().unwrap();
-    data.write_i8(v).unwrap();
-    Ok(())
+macro_rules! make_pack_with_endianess {
+    ($T:ty) => {
+        paste::item! {
+            fn [<pack_ $T>]<Endianness>(vm: &VirtualMachine, arg: &PyObjectRef, data: &mut dyn Write) -> PyResult<()>
+            where
+                Endianness: byteorder::ByteOrder,
+            {
+                let v = $T::try_from_object(vm, arg.clone())?;
+                data.[<write_$T>]::<Endianness>(v).unwrap();
+                Ok(())
+            }
+        }
+    };
 }
 
-fn pack_u8(vm: &VirtualMachine, arg: &PyObjectRef, data: &mut dyn Write) -> PyResult<()> {
-    let v = get_int(vm, arg)?.to_u8().unwrap();
-    data.write_u8(v).unwrap();
-    Ok(())
-}
+make_pack_no_endianess!(i8);
+make_pack_no_endianess!(u8);
+make_pack_with_endianess!(i16);
+make_pack_with_endianess!(u16);
+make_pack_with_endianess!(i32);
+make_pack_with_endianess!(u32);
+make_pack_with_endianess!(i64);
+make_pack_with_endianess!(u64);
+make_pack_with_endianess!(f32);
+make_pack_with_endianess!(f64);
 
 fn pack_bool(vm: &VirtualMachine, arg: &PyObjectRef, data: &mut dyn Write) -> PyResult<()> {
-    if objtype::isinstance(&arg, &vm.ctx.bool_type()) {
-        let v = if objbool::get_value(arg) { 1 } else { 0 };
-        data.write_u8(v).unwrap();
-        Ok(())
+    let v = if bool::try_from_object(vm, arg.clone())? {
+        1
     } else {
-        Err(vm.new_type_error("Expected boolean".to_string()))
-    }
-}
-
-fn pack_i16<Endianness>(
-    vm: &VirtualMachine,
-    arg: &PyObjectRef,
-    data: &mut dyn Write,
-) -> PyResult<()>
-where
-    Endianness: byteorder::ByteOrder,
-{
-    let v = get_int(vm, arg)?.to_i16().unwrap();
-    data.write_i16::<Endianness>(v).unwrap();
+        0
+    };
+    data.write_u8(v).unwrap();
     Ok(())
 }
 
-fn pack_u16<Endianness>(
-    vm: &VirtualMachine,
-    arg: &PyObjectRef,
-    data: &mut dyn Write,
-) -> PyResult<()>
-where
-    Endianness: byteorder::ByteOrder,
-{
-    let v = get_int(vm, arg)?.to_u16().unwrap();
-    data.write_u16::<Endianness>(v).unwrap();
-    Ok(())
-}
-
-fn pack_i32<Endianness>(
-    vm: &VirtualMachine,
-    arg: &PyObjectRef,
-    data: &mut dyn Write,
-) -> PyResult<()>
-where
-    Endianness: byteorder::ByteOrder,
-{
-    let v = get_int(vm, arg)?.to_i32().unwrap();
-    data.write_i32::<Endianness>(v).unwrap();
-    Ok(())
-}
-
-fn pack_u32<Endianness>(
-    vm: &VirtualMachine,
-    arg: &PyObjectRef,
-    data: &mut dyn Write,
-) -> PyResult<()>
-where
-    Endianness: byteorder::ByteOrder,
-{
-    let v = get_int(vm, arg)?.to_u32().unwrap();
-    data.write_u32::<Endianness>(v).unwrap();
-    Ok(())
-}
-
-fn pack_i64<Endianness>(
-    vm: &VirtualMachine,
-    arg: &PyObjectRef,
-    data: &mut dyn Write,
-) -> PyResult<()>
-where
-    Endianness: byteorder::ByteOrder,
-{
-    let v = get_int(vm, arg)?.to_i64().unwrap();
-    data.write_i64::<Endianness>(v).unwrap();
-    Ok(())
-}
-
-fn pack_u64<Endianness>(
-    vm: &VirtualMachine,
-    arg: &PyObjectRef,
-    data: &mut dyn Write,
-) -> PyResult<()>
-where
-    Endianness: byteorder::ByteOrder,
-{
-    let v = get_int(vm, arg)?.to_u64().unwrap();
-    data.write_u64::<Endianness>(v).unwrap();
-    Ok(())
-}
-
-fn pack_f32<Endianness>(
-    vm: &VirtualMachine,
-    arg: &PyObjectRef,
-    data: &mut dyn Write,
-) -> PyResult<()>
-where
-    Endianness: byteorder::ByteOrder,
-{
-    let v = get_float(vm, arg)? as f32;
-    data.write_f32::<Endianness>(v).unwrap();
-    Ok(())
-}
-
-fn pack_f64<Endianness>(
-    vm: &VirtualMachine,
-    arg: &PyObjectRef,
-    data: &mut dyn Write,
-) -> PyResult<()>
-where
-    Endianness: byteorder::ByteOrder,
-{
-    let v = get_float(vm, arg)?;
-    data.write_f64::<Endianness>(v).unwrap();
-    Ok(())
-}
-
-fn get_float(vm: &VirtualMachine, arg: &PyObjectRef) -> PyResult<f64> {
-    if objtype::isinstance(&arg, &vm.ctx.float_type()) {
-        Ok(objfloat::get_value(arg))
-    } else {
-        Err(vm.new_type_error("Expected float".to_string()))
-    }
-}
-
 fn pack_item<Endianness>(
     vm: &VirtualMachine,
     code: &FormatCode,