diff --git a/bool_test.v b/bool_test.v
new file mode 100644
index 0000000..1418bde
--- /dev/null
+++ b/bool_test.v
@@ -0,0 +1,171 @@
+module conf
+
+struct SingleConf {
+	some_bool bool
+}
+
+struct SingleConfDefaultFalse {
+	some_bool bool [empty_default]
+}
+
+struct SingleConfDefaultTrue {
+	some_bool bool = true
+}
+
+fn test_bool_present_no_default() {
+	mut conf := load<SingleConf>(default_path: 'test/bool.toml')!
+	assert conf == SingleConf{
+		some_bool: true
+	}
+}
+
+fn test_bool_present_no_default_env() {
+	mut conf_f := load<SingleConfDefaultFalse>(
+		default_path: 'test/bool.toml'
+		env: {
+			'SOME_BOOL': '1'
+		}
+	)!
+	assert conf_f == SingleConfDefaultFalse{
+		some_bool: true
+	}
+
+	mut conf_t := load<SingleConfDefaultTrue>(
+		default_path: 'test/bool.toml'
+		env: {
+			'SOME_BOOL': ''
+		}
+	)!
+	assert conf_t == SingleConfDefaultTrue{
+		some_bool: false
+	}
+
+	conf_f = load<SingleConfDefaultFalse>(
+		default_path: 'test/bool.toml'
+		env: {
+			'TEST_SOME_BOOL': 'true'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf_f == SingleConfDefaultFalse{
+		some_bool: true
+	}
+}
+
+fn test_bool_absent_no_default() {
+	conf := load<SingleConf>(default_path: 'test/empty.toml') or { return }
+	assert false
+}
+
+fn test_bool_absent_no_default_env() {
+	mut conf_f := load<SingleConfDefaultFalse>(
+		default_path: 'test/bool.toml'
+		env: {
+			'SOME_BOOL': '1'
+		}
+	)!
+	assert conf_f == SingleConfDefaultFalse{
+		some_bool: true
+	}
+
+	mut conf_t := load<SingleConfDefaultTrue>(
+		default_path: 'test/bool.toml'
+		env: {
+			'SOME_BOOL': ''
+		}
+	)!
+	assert conf_t == SingleConfDefaultTrue{
+		some_bool: false
+	}
+
+	conf_f = load<SingleConfDefaultFalse>(
+		default_path: 'test/bool.toml'
+		env: {
+			'TEST_SOME_BOOL': '1'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf_f == SingleConfDefaultFalse{
+		some_bool: true
+	}
+}
+
+fn test_bool_present_default() {
+	conf := load<SingleConfDefaultFalse>(default_path: 'test/bool.toml')!
+	assert conf == SingleConfDefaultFalse{
+		some_bool: true
+	}
+}
+
+fn test_bool_present_default_env() {
+	mut conf_f := load<SingleConfDefaultFalse>(
+		default_path: 'test/bool.toml'
+		env: {
+			'SOME_BOOL': '1'
+		}
+	)!
+	assert conf_f == SingleConfDefaultFalse{
+		some_bool: true
+	}
+
+	mut conf_t := load<SingleConfDefaultTrue>(
+		default_path: 'test/bool.toml'
+		env: {
+			'SOME_BOOL': ''
+		}
+	)!
+	assert conf_t == SingleConfDefaultTrue{
+		some_bool: false
+	}
+
+	conf_f = load<SingleConfDefaultFalse>(
+		default_path: 'test/bool.toml'
+		env: {
+			'TEST_SOME_BOOL': '1'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf_f == SingleConfDefaultFalse{
+		some_bool: true
+	}
+}
+
+fn test_bool_absent_default() {
+	conf := load<SingleConfDefaultTrue>(default_path: 'test/empty.toml')!
+	assert conf == SingleConfDefaultTrue{
+		some_bool: true
+	}
+}
+
+fn test_bool_absent_default_env() {
+	mut conf_f := load<SingleConfDefaultFalse>(
+		default_path: 'test/empty.toml'
+		env: {
+			'SOME_BOOL': '1'
+		}
+	)!
+	assert conf_f == SingleConfDefaultFalse{
+		some_bool: true
+	}
+
+	mut conf_t := load<SingleConfDefaultTrue>(
+		default_path: 'test/empty.toml'
+		env: {
+			'SOME_BOOL': ''
+		}
+	)!
+	assert conf_t == SingleConfDefaultTrue{
+		some_bool: false
+	}
+
+	conf_f = load<SingleConfDefaultFalse>(
+		default_path: 'test/empty.toml'
+		env: {
+			'TEST_SOME_BOOL': 'true'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf_f == SingleConfDefaultFalse{
+		some_bool: true
+	}
+}
diff --git a/conf.v b/conf.v
index c3865ca..cf2405e 100644
--- a/conf.v
+++ b/conf.v
@@ -2,25 +2,33 @@ module conf
 
 import os
 import toml
+import datatypes { Set }
+
+[params]
+pub struct LoadConfig {
+	prefix       string
+	file_suffix  string = '_FILE'
+	default_path string
+	// Allows overwriting
+	env map[string]string = os.environ()
+}
 
 // get_env_var tries to read the contents of the given environment variable. It
 // looks for either `${env.prefix}${field_name.to_upper()}` or
 // `${env.prefix}${field_name.to_upper()}${env.file_suffix}`, returning the
 // contents of the file instead if the latter. If both or neither exist, the
-// function returns an error.
-fn get_env_var(prefix string, field_name string, file_suffix string) !string {
-	env_var_name := '$prefix$field_name.to_upper()'
-	env_file_name := '$prefix$field_name.to_upper()$file_suffix'
-	env_var := os.getenv(env_var_name)
-	env_file := os.getenv(env_file_name)
+// function returns an error. It returns two values, with the first indicating
+// whether the env vars were actually present.
+fn (ld LoadConfig) get_env_var(field_name string) !(bool, string) {
+	env_var_name := '$ld.prefix$field_name.to_upper()'
+	env_file_name := '$ld.prefix$field_name.to_upper()$ld.file_suffix'
 
-	// If both are missing, we return an empty string
-	if env_var == '' && env_file == '' {
-		return ''
+	if env_var_name !in ld.env && env_file_name !in ld.env {
+		return false, ''
 	}
 
 	// If they're both set, we report a conflict
-	if env_var != '' && env_file != '' {
+	if env_var_name in ld.env && env_file_name in ld.env {
 		return error('Only one of $env_var_name or $env_file_name can be defined.')
 	}
 
@@ -28,36 +36,40 @@ fn get_env_var(prefix string, field_name string, file_suffix string) !string {
 	// I'm pretty sure this also prevents variable ending in _FILE (e.g.
 	// VIETER_LOG_FILE) from being mistakingely read as an _FILE suffixed env
 	// var.
-	if env_var != '' {
-		return env_var
+	if env_var_name in ld.env {
+		return true, ld.env[env_var_name]
 	}
 
 	// Otherwise, we process the file
-	return os.read_file(env_file) or {
+	return true, os.read_file(ld.env[env_file_name]) or {
 		error('Failed to read file defined in $env_file_name: ${err.msg()}.')
 	}
 }
 
-[params]
-pub struct LoadConfig {
-	prefix       string
-	file_suffix  string = '_FILE'
-	default_path string
-}
-
 // load<T> attempts to create an object of type T from the given path to a toml
 // file & environment variables. For each field, it will select either a value
 // given from an environment variable, a value defined in the config file or a
 // configured default if present, in that order.
-pub fn load<T>(conf LoadConfig) !T {
+pub fn load<T>(ld LoadConfig) !T {
+	// Ensure all struct fields consist of supported types
+	$for field in T.fields {
+		$if field.typ is string || field.typ is int || field.typ is bool {
+		} $else {
+			// I'd prefer changing this to $compile_error, but as of V 0.3.2,
+			// this seems to be bugged. If I replace this call with a
+			// $compile_error call, the error *always* happens, even if all
+			// fields are correct.
+			return error('Field $field.name is of an unsupported type.')
+		}
+	}
 	mut res := T{}
 
 	// This array allows us to determine later whether the variable is actually
 	// zero or just a null'ed struct field
-	mut has_value := map[string]bool{}
+	mut has_value := Set<string>{}
 
 	// Later, this could be read from an env var as well.
-	path := conf.default_path
+	path := ld.default_path
 
 	if os.exists(path) {
 		// We don't use reflect here because reflect also sets any fields not
@@ -72,35 +84,60 @@ pub fn load<T>(conf LoadConfig) !T {
 					res.$(field.name) = s.string()
 				} $else $if field.typ is int {
 					res.$(field.name) = s.int()
-					// This seems to not work in V 0.3.2
-					//} $else {
-					//	$compile_error('Unsupported config struct field type detected.')
+				} $else $if field.typ is bool {
+					res.$(field.name) = s.bool()
 				}
 
-				has_value[field.name] = true
+				has_value.add(field.name)
 			}
 		}
 	}
 
 	$for field in T.fields {
-		env_value := get_env_var(conf.prefix, field.name, conf.file_suffix)!
+		env_present, env_value := ld.get_env_var(field.name)!
 
 		// The value of an env var will always take precedence over the toml
 		// file.
-		if env_value != '' {
+		if env_present {
 			$if field.typ is string {
 				res.$(field.name) = env_value
 			} $else $if field.typ is int {
 				res.$(field.name) = env_value.int()
-				// This seems to not work in V 0.3.2
-				//} $else {
-				//	$compile_error('Unsupported config struct field type detected.')
+			} $else $if field.typ is bool {
+				// Env var accepts '1' and 'true' as truthy, everything else
+				// evaluates to false
+				res.$(field.name) = env_value in ['1', 'true']
 			}
 
-			has_value[field.name] = true
+			has_value.add(field.name)
 		}
 
-		if !(has_value[field.name] or { false }) {
+		// Finally, if there's no env var present either, we check whether the
+		// variable has a default value. Variables defined with an "empty
+		// default" will always be marked as containing a value.
+		if 'empty_default' in field.attrs {
+			has_value.add(field.name)
+		} else if !has_value.exists(field.name) {
+			mut has_default := false
+
+			$if field.typ is string {
+				has_default = res.$(field.name) != ''
+			} $else $if field.typ is int {
+				has_default = res.$(field.name) != 0
+			} $else $if field.typ is bool {
+				// This explicit comparison is required as the type system gets
+				// a bit confused otherwise
+				has_default = res.$(field.name) == true
+			}
+
+			if has_default {
+				has_value.add(field.name)
+			}
+		}
+
+		// If there's no value provided in any way, we notify the user with an
+		// error.
+		if !has_value.exists(field.name) {
 			return error("Missing config variable '$field.name' with no provided default. Either add it to the config file or provide it using an environment variable.")
 		}
 	}
diff --git a/conf_test.v b/conf_test.v
index 72e7703..4877724 100644
--- a/conf_test.v
+++ b/conf_test.v
@@ -1,43 +1,10 @@
 module conf
 
-struct SimpleConf {
-	some_int    int
-	some_string string
+struct WrongTypeConfig {
+	f map[string]string
 }
 
-struct SimpleConfDefaults {
-	some_int    int    = 3
-	some_string string = 'hi'
-}
-
-fn test_simple() {
-	conf := load<SimpleConf>(default_path: 'test/test_simple.toml')!
-	assert conf == SimpleConf{
-		some_int: 2
-		some_string: 'hi'
-	}
-}
-
-fn test_zeroed() {
-	conf := load<SimpleConf>(default_path: 'test/test_zeroed.toml')!
-	assert conf == SimpleConf{
-		some_int: 0
-		some_string: ''
-	}
-}
-
-fn test_zeroed_defaults() {
-	conf := load<SimpleConfDefaults>(default_path: 'test/test_zeroed.toml')!
-	assert conf == SimpleConfDefaults{
-		some_int: 0
-		some_string: ''
-	}
-}
-
-fn test_defaults() {
-	conf := load<SimpleConfDefaults>(default_path: 'test/test_single_value.toml')!
-	assert conf == SimpleConfDefaults{
-		some_int: 3
-		some_string: 'hi'
-	}
+fn test_wrong_type() {
+	conf := load<WrongTypeConfig>() or { return }
+	assert false
 }
diff --git a/int_test.v b/int_test.v
new file mode 100644
index 0000000..defddc8
--- /dev/null
+++ b/int_test.v
@@ -0,0 +1,188 @@
+module conf
+
+struct SingleConf {
+	some_int int
+}
+
+struct SingleConfDefault {
+	some_int int = 2
+}
+
+fn test_int_present_no_default() {
+	mut conf := load<SingleConf>(default_path: 'test/int.toml')!
+	assert conf == SingleConf{
+		some_int: 1
+	}
+
+	conf = load<SingleConf>(default_path: 'test/int_zero.toml')!
+	assert conf == SingleConf{
+		some_int: 0
+	}
+}
+
+fn test_int_present_no_default_env() {
+	mut conf := load<SingleConf>(
+		default_path: 'test/int.toml'
+		env: {
+			'SOME_INT': '3'
+		}
+	)!
+	assert conf == SingleConf{
+		some_int: 3
+	}
+
+	conf = load<SingleConf>(
+		default_path: 'test/int.toml'
+		env: {
+			'SOME_INT': ''
+		}
+	)!
+	assert conf == SingleConf{
+		some_int: 0
+	}
+
+	conf = load<SingleConf>(
+		default_path: 'test/int.toml'
+		env: {
+			'TEST_SOME_INT': '3'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf == SingleConf{
+		some_int: 3
+	}
+}
+
+fn test_int_absent_no_default() {
+	conf := load<SingleConf>(default_path: 'test/empty.toml') or { return }
+	assert false
+}
+
+fn test_int_absent_no_default_env() {
+	mut conf := load<SingleConf>(
+		default_path: 'test/int.toml'
+		env: {
+			'SOME_INT': '3'
+		}
+	)!
+	assert conf == SingleConf{
+		some_int: 3
+	}
+
+	conf = load<SingleConf>(
+		default_path: 'test/int.toml'
+		env: {
+			'SOME_INT': ''
+		}
+	)!
+	assert conf == SingleConf{
+		some_int: 0
+	}
+
+	conf = load<SingleConf>(
+		default_path: 'test/int.toml'
+		env: {
+			'TEST_SOME_INT': '3'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf == SingleConf{
+		some_int: 3
+	}
+}
+
+fn test_int_present_default() {
+	conf := load<SingleConfDefault>(default_path: 'test/int.toml')!
+	assert conf == SingleConfDefault{
+		some_int: 1
+	}
+}
+
+fn test_int_present_default_env() {
+	mut conf := load<SingleConfDefault>(
+		default_path: 'test/int.toml'
+		env: {
+			'SOME_INT': '3'
+		}
+	)!
+	assert conf == SingleConfDefault{
+		some_int: 3
+	}
+
+	conf = load<SingleConfDefault>(
+		default_path: 'test/int.toml'
+		env: {
+			'SOME_INT': ''
+		}
+	)!
+	assert conf == SingleConfDefault{
+		some_int: 0
+	}
+
+	conf = load<SingleConfDefault>(
+		default_path: 'test/int.toml'
+		env: {
+			'TEST_SOME_INT': '3'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf == SingleConfDefault{
+		some_int: 3
+	}
+}
+
+fn test_int_absent_default() {
+	conf := load<SingleConfDefault>(default_path: 'test/empty.toml')!
+	assert conf == SingleConfDefault{
+		some_int: 2
+	}
+}
+
+fn test_int_absent_default_env() {
+	mut conf := load<SingleConfDefault>(
+		default_path: 'test/empty.toml'
+		env: {
+			'SOME_INT': '3'
+		}
+	)!
+	assert conf == SingleConfDefault{
+		some_int: 3
+	}
+
+	conf = load<SingleConfDefault>(
+		default_path: 'test/empty.toml'
+		env: {
+			'SOME_INT': ''
+		}
+	)!
+	assert conf == SingleConfDefault{
+		some_int: 0
+	}
+
+	conf = load<SingleConfDefault>(
+		default_path: 'test/empty.toml'
+		env: {
+			'TEST_SOME_INT': '3'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf == SingleConfDefault{
+		some_int: 3
+	}
+}
+
+struct SingleConfDefaultEmpty {
+	some_int int [empty_default]
+}
+
+fn test_int_absent_default_empty() {
+	conf := load<SingleConfDefaultEmpty>(default_path: 'test/empty.toml')!
+	assert conf == SingleConfDefaultEmpty{
+		some_int: 0
+	}
+}
+
+// fn test_int_wrong_type() {
+//	conf := load<SingleConf>(default_path: 'test/int_wrong_type.toml') or { return }
+//	assert false
+//}
diff --git a/string_test.v b/string_test.v
new file mode 100644
index 0000000..9c7a6a9
--- /dev/null
+++ b/string_test.v
@@ -0,0 +1,183 @@
+module conf
+
+struct SingleConf {
+	some_string string
+}
+
+struct SingleConfDefault {
+	some_string string = 'default'
+}
+
+fn test_string_present_no_default() {
+	mut conf := load<SingleConf>(default_path: 'test/string.toml')!
+	assert conf == SingleConf{
+		some_string: 'hi'
+	}
+
+	conf = load<SingleConf>(default_path: 'test/string_empty.toml')!
+	assert conf == SingleConf{
+		some_string: ''
+	}
+}
+
+fn test_string_present_no_default_env() {
+	mut conf := load<SingleConf>(
+		default_path: 'test/string.toml'
+		env: {
+			'SOME_STRING': 'env'
+		}
+	)!
+	assert conf == SingleConf{
+		some_string: 'env'
+	}
+
+	conf = load<SingleConf>(
+		default_path: 'test/string.toml'
+		env: {
+			'SOME_STRING': ''
+		}
+	)!
+	assert conf == SingleConf{
+		some_string: ''
+	}
+
+	conf = load<SingleConf>(
+		default_path: 'test/string.toml'
+		env: {
+			'TEST_SOME_STRING': 'env'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf == SingleConf{
+		some_string: 'env'
+	}
+}
+
+fn test_string_absent_no_default() {
+	conf := load<SingleConf>(default_path: 'test/empty.toml') or { return }
+	assert false
+}
+
+fn test_string_absent_no_default_env() {
+	mut conf := load<SingleConf>(
+		default_path: 'test/string.toml'
+		env: {
+			'SOME_STRING': 'env'
+		}
+	)!
+	assert conf == SingleConf{
+		some_string: 'env'
+	}
+
+	conf = load<SingleConf>(
+		default_path: 'test/string.toml'
+		env: {
+			'SOME_STRING': ''
+		}
+	)!
+	assert conf == SingleConf{
+		some_string: ''
+	}
+
+	conf = load<SingleConf>(
+		default_path: 'test/string.toml'
+		env: {
+			'TEST_SOME_STRING': 'env'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf == SingleConf{
+		some_string: 'env'
+	}
+}
+
+fn test_string_present_default() {
+	conf := load<SingleConfDefault>(default_path: 'test/string.toml')!
+	assert conf == SingleConfDefault{
+		some_string: 'hi'
+	}
+}
+
+fn test_string_present_default_env() {
+	mut conf := load<SingleConfDefault>(
+		default_path: 'test/string.toml'
+		env: {
+			'SOME_STRING': 'env'
+		}
+	)!
+	assert conf == SingleConfDefault{
+		some_string: 'env'
+	}
+
+	conf = load<SingleConfDefault>(
+		default_path: 'test/string.toml'
+		env: {
+			'SOME_STRING': ''
+		}
+	)!
+	assert conf == SingleConfDefault{
+		some_string: ''
+	}
+
+	conf = load<SingleConfDefault>(
+		default_path: 'test/string.toml'
+		env: {
+			'TEST_SOME_STRING': 'env'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf == SingleConfDefault{
+		some_string: 'env'
+	}
+}
+
+fn test_string_absent_default() {
+	conf := load<SingleConfDefault>(default_path: 'test/empty.toml')!
+	assert conf == SingleConfDefault{
+		some_string: 'default'
+	}
+}
+
+fn test_string_absent_default_env() {
+	mut conf := load<SingleConfDefault>(
+		default_path: 'test/empty.toml'
+		env: {
+			'SOME_STRING': 'env'
+		}
+	)!
+	assert conf == SingleConfDefault{
+		some_string: 'env'
+	}
+
+	conf = load<SingleConfDefault>(
+		default_path: 'test/empty.toml'
+		env: {
+			'SOME_STRING': ''
+		}
+	)!
+	assert conf == SingleConfDefault{
+		some_string: ''
+	}
+
+	conf = load<SingleConfDefault>(
+		default_path: 'test/empty.toml'
+		env: {
+			'TEST_SOME_STRING': 'env'
+		}
+		prefix: 'TEST_'
+	)!
+	assert conf == SingleConfDefault{
+		some_string: 'env'
+	}
+}
+
+struct SingleConfDefaultEmpty {
+	some_string string [empty_default]
+}
+
+fn test_string_absent_default_empty() {
+	conf := load<SingleConfDefaultEmpty>(default_path: 'test/empty.toml')!
+	assert conf == SingleConfDefaultEmpty{
+		some_string: ''
+	}
+}
diff --git a/test/bool.toml b/test/bool.toml
new file mode 100644
index 0000000..a3e45e2
--- /dev/null
+++ b/test/bool.toml
@@ -0,0 +1 @@
+some_bool = true
diff --git a/test/empty.toml b/test/empty.toml
new file mode 100644
index 0000000..e69de29
diff --git a/test/int.toml b/test/int.toml
new file mode 100644
index 0000000..b8326e0
--- /dev/null
+++ b/test/int.toml
@@ -0,0 +1 @@
+some_int = 1
diff --git a/test/int_wrong_type.toml b/test/int_wrong_type.toml
new file mode 100644
index 0000000..e63b96b
--- /dev/null
+++ b/test/int_wrong_type.toml
@@ -0,0 +1 @@
+some_int = '1'
diff --git a/test/int_zero.toml b/test/int_zero.toml
new file mode 100644
index 0000000..4dd4d46
--- /dev/null
+++ b/test/int_zero.toml
@@ -0,0 +1 @@
+some_int = 0
diff --git a/test/test_single_value.toml b/test/string.toml
similarity index 100%
rename from test/test_single_value.toml
rename to test/string.toml
diff --git a/test/test_zeroed.toml b/test/string_empty.toml
similarity index 56%
rename from test/test_zeroed.toml
rename to test/string_empty.toml
index ce4dd51..8866b17 100644
--- a/test/test_zeroed.toml
+++ b/test/string_empty.toml
@@ -1,2 +1 @@
-some_int = 0
 some_string = ""
diff --git a/test/test_simple.toml b/test/test_simple.toml
deleted file mode 100644
index 489eea3..0000000
--- a/test/test_simple.toml
+++ /dev/null
@@ -1,2 +0,0 @@
-some_int = 2
-some_string = "hi"