diff --git a/phasm/typer.py b/phasm/typer.py
index 07f7f33..de55ef3 100644
--- a/phasm/typer.py
+++ b/phasm/typer.py
@@ -83,8 +83,12 @@ def expression(ctx: 'Context', inp: ourlang.Expression) -> 'TypeVar':
 
     if isinstance(inp, ourlang.FunctionCall):
         assert inp.function.returns_type_var is not None
-        if inp.function.posonlyargs:
-            raise NotImplementedError('TODO: Functions with arguments')
+
+        for param, expr in zip(inp.function.posonlyargs, inp.arguments):
+            assert param.type_var is not None
+
+            arg = expression(ctx, expr)
+            ctx.unify(param.type_var, arg)
 
         return inp.function.returns_type_var
 
@@ -105,6 +109,8 @@ def function(ctx: 'Context', inp: ourlang.Function) -> None:
 def module_constant_def(ctx: 'Context', inp: ourlang.ModuleConstantDef) -> None:
     inp.type_var = _convert_old_type(ctx, inp.type, inp.name)
     constant(ctx, inp.constant)
+
+    assert inp.constant.type_var is not None
     ctx.unify(inp.type_var, inp.constant.type_var)
 
 def module(inp: ourlang.Module) -> None:
diff --git a/tests/integration/test_simple.py b/tests/integration/test_simple.py
index aace8a7..fdad1e4 100644
--- a/tests/integration/test_simple.py
+++ b/tests/integration/test_simple.py
@@ -3,6 +3,7 @@ import pytest
 from .helpers import Suite
 
 ALL_INT_TYPES = ['u8', 'u32', 'u64', 'i32', 'i64']
+COMLETE_INT_TYPES = ['u32', 'u64', 'i32', 'i64']
 ALL_FLOAT_TYPES = ['f32', 'f64']
 
 TYPE_MAP = {
@@ -45,7 +46,7 @@ def testEntry() -> {type_}:
     assert TYPE_MAP[type_] == type(result.returned_value)
 
 @pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ALL_INT_TYPES)
+@pytest.mark.parametrize('type_', COMLETE_INT_TYPES)
 def test_addition_int(type_):
     code_py = f"""
 @exported
@@ -73,7 +74,7 @@ def testEntry() -> {type_}:
     assert TYPE_MAP[type_] == type(result.returned_value)
 
 @pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ALL_INT_TYPES)
+@pytest.mark.parametrize('type_', COMLETE_INT_TYPES)
 def test_subtraction_int(type_):
     code_py = f"""
 @exported
@@ -390,8 +391,8 @@ def helper(left: i32, right: i32) -> i32:
     assert 7 == result.returned_value
 
 @pytest.mark.integration_test
-@pytest.mark.parametrize('type_', COMPLETE_SIMPLE_TYPES)
-def test_call_with_expression(type_):
+@pytest.mark.parametrize('type_', COMLETE_INT_TYPES)
+def test_call_with_expression_int(type_):
     code_py = f"""
 @exported
 def testEntry() -> {type_}:
@@ -406,6 +407,23 @@ def helper(left: {type_}, right: {type_}) -> {type_}:
     assert 22 == result.returned_value
     assert TYPE_MAP[type_] == type(result.returned_value)
 
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_FLOAT_TYPES)
+def test_call_with_expression_float(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return helper(10.078125 + 90.046875, 63.0 + 5.0)
+
+def helper(left: {type_}, right: {type_}) -> {type_}:
+    return left - right
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 32.125 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
 @pytest.mark.integration_test
 @pytest.mark.skip('Not yet implemented')
 def test_assign():