diff --git a/compiler/parser.v b/compiler/parser.v
index 2fbfd5e29d..d7affbd86c 100644
--- a/compiler/parser.v
+++ b/compiler/parser.v
@@ -139,8 +139,8 @@ fn (p mut Parser) parse() {
 	// fully qualify the module name, eg base64 to encoding.base64
 	fq_mod := p.table.qualify_module(p.mod, p.file_path)
 	p.table.register_package(fq_mod)
-	// replace "." with "__" in module name for C variable names
-	p.mod = fq_mod.replace('.', '__')
+	// replace "." with "_dot_" in module name for C variable names
+	p.mod = fq_mod.replace('.', '_dot_')
 	if p.run == .imports {
 		for p.tok == .key_import && p.peek() != .key_const {
 			p.import_statement()
@@ -1308,8 +1308,8 @@ fn (p mut Parser) name_expr() string {
 		mut pkg := name
 		// must be aliased module
 		if name != p.mod && p.import_table.known_alias(name) {
-			// we replaced "." with "__" in p.mod for C variable names, do same here.
-			pkg = p.import_table.resolve_alias(name).replace('.', '__')
+			// we replaced "." with "_dot_" in p.mod for C variable names, do same here.
+			pkg = p.import_table.resolve_alias(name).replace('.', '_dot_')
 		}
 		p.next()
 		p.check(.dot)
@@ -1435,7 +1435,7 @@ fn (p mut Parser) name_expr() string {
 			// If orig_name is a pkg, then printing undefined: `pkg` tells us nothing
 			// if p.table.known_pkg(orig_name) {
 			if p.table.known_pkg(orig_name) || p.import_table.known_alias(orig_name) {
-				name = name.replace('__', '.')
+				name = name.replace('__', '.').replace('_dot_', '.')
 				p.error('undefined: `$name`')
 			}
 			else {
diff --git a/vlib/hash/crc32/crc32.v b/vlib/hash/crc32/crc32.v
new file mode 100644
index 0000000000..606f839abe
--- /dev/null
+++ b/vlib/hash/crc32/crc32.v
@@ -0,0 +1,59 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+// This is a very basic crc32 implementation
+// at the moment with no architecture optimizations
+module crc32
+
+// polynomials
+const (
+	IEEE       = 0xedb88320
+	Castagnoli = 0x82f63b78
+	Koopman    = 0xeb31d82e
+)
+
+struct Crc32 {
+mut:
+	table []u32
+}
+
+fn(c mut Crc32) generate_table(poly int) {
+	for i := 0; i < 256; i++ {
+		mut crc := u32(i)
+		for j := 0; j < 8; j++ {
+			if crc&u32(1) == u32(1) {
+				crc = u32((crc >> u32(1)) ^ poly)
+			} else {
+				crc >>= u32(1)
+			}
+		}
+		c.table << crc
+	}
+}
+ 
+fn(c &Crc32) sum_32(s string) u32 {
+	mut crc := ~u32(0)
+	for i := 0; i < s.len; i++ {
+		crc = c.table[byte(crc)^s[i]] ^ u32(crc >> u32(8))
+	}
+	return ~crc
+}
+
+pub fn(c &Crc32) checksum(s string) u32 {
+	return c.sum_32(s)
+}
+
+// pass the polinomial to use
+pub fn new(poly int) *Crc32 {
+	mut c := &Crc32{}
+	c.generate_table(poly)
+	return c
+}
+
+// calculate crc32 using IEEE
+pub fn sum(s string) u32 {
+	mut c := new(IEEE)
+	return c.sum_32(s)
+}
+
diff --git a/vlib/hash/crc32/crc32_test.v b/vlib/hash/crc32/crc32_test.v
new file mode 100644
index 0000000000..4aad09c614
--- /dev/null
+++ b/vlib/hash/crc32/crc32_test.v
@@ -0,0 +1,10 @@
+import hash.crc32
+
+fn test_hash_crc32() {
+	assert crc32.sum('testing crc32') == u32(1212124400)
+	assert crc32.sum('testing crc32').hex() == '0x483f8cf0'
+
+	c := crc32.new(crc32.IEEE)
+	assert c.checksum('testing crc32 again') == u32(1420327025)
+	assert c.checksum('testing crc32 again').hex() == '0x54a87871'
+}
\ No newline at end of file