diff --git a/.gitignore b/.gitignore
index e92d5a5f69..905d2bf174 100644
--- a/.gitignore
+++ b/.gitignore
@@ -130,3 +130,4 @@ vls.log
 wasm.v
 TAGS
 tags
+vlib/builtin/js/*.js
diff --git a/cmd/tools/vtest-all.v b/cmd/tools/vtest-all.v
index 4414d716df..2f8e4df368 100644
--- a/cmd/tools/vtest-all.v
+++ b/cmd/tools/vtest-all.v
@@ -113,6 +113,12 @@ fn get_all_commands() []Command {
 		runcmd: .execute
 		expect: "['arg1', 'arg2']1.0"
 	}
+	res << Command{
+		line: '${vexe} -o calling_c.exe run examples/call_c_from_v/main.c.v'
+		okmsg: 'V can run main.c.v files'
+		runcmd: .execute
+		contains: 'V can call C functions like puts too.'
+	}
 	$if linux || macos {
 		res << Command{
 			line: '${vexe} run examples/hello_world.v'
diff --git a/examples/call_c_from_v/main.c.v b/examples/call_c_from_v/main.c.v
new file mode 100644
index 0000000000..fd66439b13
--- /dev/null
+++ b/examples/call_c_from_v/main.c.v
@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+fn C.puts(&char) int
+
+fn main() {
+	C.puts(c'V can call C functions like `puts` too.')
+}
diff --git a/vlib/builtin/js/int.js.v b/vlib/builtin/js/int.js.v
index b3486ba565..c89d1c71d9 100644
--- a/vlib/builtin/js/int.js.v
+++ b/vlib/builtin/js/int.js.v
@@ -108,9 +108,11 @@ pub fn (x u16) hex() string {
 }
 
 pub fn (x i8) hex() string {
-	res := ''
+	mut res := ''
 	#res.str = x.val.toString(16)
-
+	if res.len < 2 {
+		res = '0' + res
+	}
 	return res
 }
 
@@ -136,9 +138,11 @@ pub fn (x int_literal) hex() string {
 }
 
 pub fn (x u8) hex() string {
-	res := ''
+	mut res := ''
 	#res.str = x.val.toString(16)
-
+	if res.len < 2 {
+		res = '0' + res
+	}
 	return res
 }
 
diff --git a/vlib/builtin/js/int_test.js.v b/vlib/builtin/js/int_test.js.v
index dcd79841c8..accfdeaa35 100644
--- a/vlib/builtin/js/int_test.js.v
+++ b/vlib/builtin/js/int_test.js.v
@@ -109,7 +109,7 @@ fn test_hex() {
 	// assert u64(-1).hex() == 'ffffffffffffffff'
 	// signed tests
 	// assert i8(-1).hex() == 'ff'
-	assert i8(12).hex() == 'c'
+	assert i8(12).hex() == '0c'
 	assert i16(32767).hex() == '7fff'
 	assert int(2147483647).hex() == '7fffffff'
 	assert i64(9223372036854775807).hex() == '7fffffffffffffff'
@@ -202,35 +202,35 @@ fn test_int_to_hex() {
 	st1 := [u8(0x41)].repeat(100)
 	assert st1.hex() == '41'.repeat(100)*/
 	// --- int to hex tests
-	c0 := 12
+	c := 12
 	// 8Bit
-	assert u8(0).hex() == '0'
-	assert u8(c0).hex() == 'c'
-	assert i8(c0).hex() == 'c'
+	assert u8(0).hex() == '00'
+	assert u8(c).hex() == '0c'
+	assert i8(c).hex() == '0c'
 	assert u8(127).hex() == '7f'
 	assert i8(127).hex() == '7f'
 	assert u8(255).hex() == 'ff'
 	// assert u8(-1).hex() == 'ff'
 	// 16bit
 	assert u16(0).hex() == '0'
-	assert i16(c0).hex() == 'c'
-	assert u16(c0).hex() == 'c'
+	assert i16(c).hex() == 'c'
+	assert u16(c).hex() == 'c'
 	assert i16(32767).hex() == '7fff'
 	assert u16(32767).hex() == '7fff'
 	// assert i16(-1).hex() == 'ffff'
 	assert u16(65535).hex() == 'ffff'
 	// 32bit
 	assert u32(0).hex() == '0'
-	assert c0.hex() == 'c'
-	assert u32(c0).hex() == 'c'
+	assert c.hex() == 'c'
+	assert u32(c).hex() == 'c'
 	assert 2147483647.hex() == '7fffffff'
 	assert u32(2147483647).hex() == '7fffffff'
 	// assert (-1).hex() == 'ffffffffffffffff'
 	// assert u32(4294967295).hex() == 'ffffffff'
 	// 64 bit
 	assert u64(0).hex() == '0'
-	assert i64(c0).hex() == 'c'
-	assert u64(c0).hex() == 'c'
+	assert i64(c).hex() == 'c'
+	assert u64(c).hex() == 'c'
 	assert i64(9223372036854775807).hex() == '7fffffffffffffff'
 	assert u64(9223372036854775807).hex() == '7fffffffffffffff'
 	// assert i64(-1).hex() == 'ffffffffffffffff'
diff --git a/vlib/v/pref/default.v b/vlib/v/pref/default.v
index ff60171371..ff80835564 100644
--- a/vlib/v/pref/default.v
+++ b/vlib/v/pref/default.v
@@ -63,6 +63,9 @@ pub fn (mut p Preferences) fill_with_defaults() {
 	if p.out_name == '' {
 		filename := os.file_name(rpath).trim_space()
 		mut base := filename.all_before_last('.')
+		if os.file_ext(base) in ['.c', '.js', '.wasm'] {
+			base = base.all_before_last('.')
+		}
 		if base == '' {
 			// The file name is just `.v` or `.vsh` or `.*`
 			base = filename