diff --git a/phasm/compiler.py b/phasm/compiler.py
index b686dac..5ba2793 100644
--- a/phasm/compiler.py
+++ b/phasm/compiler.py
@@ -312,6 +312,12 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
     if isinstance(inp, ourlang.Subscript):
         assert isinstance(inp.varref.type3, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
 
+        if inp.varref.type3 is type3types.bytes:
+            expression(wgn, inp.varref)
+            expression(wgn, inp.index)
+            wgn.call(stdlib_types.__subscript_bytes__)
+            return
+
         if isinstance(inp.varref.type3, type3types.AppliedType3):
             if inp.varref.type3.base == type3types.static_array:
                 assert 1 == len(inp.varref.type3.args)
diff --git a/phasm/type3/constraints.py b/phasm/type3/constraints.py
index 34a0158..6307d90 100644
--- a/phasm/type3/constraints.py
+++ b/phasm/type3/constraints.py
@@ -394,7 +394,11 @@ class CanBeSubscriptedConstraint(ConstraintBase):
                     SameTypeConstraint(self.type3.args[self.index.value], self.ret_type3, comment=f'Tuple subscript index {self.index.value}'),
                 ]
 
-        # FIXME: bytes
+        if self.type3 is types.bytes:
+            return [
+                SameTypeConstraint(types.u32, self.index_type3, comment='([]) :: bytes -> u32 -> u8'),
+                SameTypeConstraint(types.u8, self.ret_type3, comment='([]) :: bytes -> u32 -> u8'),
+            ]
 
         if self.type3.name in types.LOOKUP_TABLE:
             return Error(f'{self.type3.name} cannot be subscripted')
diff --git a/tests/integration/test_lang/test_bytes.py b/tests/integration/test_lang/test_bytes.py
index 6df111a..af3f78d 100644
--- a/tests/integration/test_lang/test_bytes.py
+++ b/tests/integration/test_lang/test_bytes.py
@@ -1,5 +1,7 @@
 import pytest
 
+from phasm.type3.entry import Type3Exception
+
 from ..helpers import Suite
 
 @pytest.mark.integration_test
@@ -51,3 +53,32 @@ def testEntry(f: bytes) -> u8:
     result = Suite(code_py).run_code(b'Short', b'Long' * 100)
 
     assert 0 == result.returned_value
+
+@pytest.mark.integration_test
+def test_function_call_element_ok():
+    code_py = """
+@exported
+def testEntry(f: bytes) -> u8:
+    return helper(f[0])
+
+def helper(x: u8) -> u8:
+    return x
+"""
+
+    result = Suite(code_py).run_code(b'Short')
+
+    assert 83 == result.returned_value
+
+@pytest.mark.integration_test
+def test_function_call_element_type_mismatch():
+    code_py = """
+@exported
+def testEntry(f: bytes) -> u64:
+    return helper(f[0])
+
+def helper(x: u64) -> u64:
+    return x
+"""
+
+    with pytest.raises(Type3Exception, match=r'u64 must be u8 instead'):
+        Suite(code_py).run_code()