diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index faf1db3939..f6fe7ac2d2 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -626,6 +626,7 @@ pub:
 	expr      Expr // `buf`
 	arg       Expr // `n` in `string(buf, n)`
 	typ       table.Type // `string`
+	typname   string
 mut:
 	expr_type table.Type // `byteptr`
 	has_arg   bool
diff --git a/vlib/v/ast/str.v b/vlib/v/ast/str.v
index 25d4d16800..d51a21b1d3 100644
--- a/vlib/v/ast/str.v
+++ b/vlib/v/ast/str.v
@@ -72,7 +72,7 @@ pub fn (x Expr) str() string {
 			return it.name
 		}
 		InfixExpr {
-			return '(${it.left.str()} $it.op.str() ${it.right.str()})'
+			return '${it.left.str()} $it.op.str() ${it.right.str()}'
 		}
 		PrefixExpr {
 			return it.op.str() + it.right.str()
@@ -80,6 +80,9 @@ pub fn (x Expr) str() string {
 		IntegerLiteral {
 			return it.val
 		}
+		FloatLiteral {
+			return it.val
+		}
 		StringLiteral {
 			return '"$it.val"'
 		}
@@ -113,6 +116,9 @@ pub fn (x Expr) str() string {
 		IndexExpr {
 			return '${it.left.str()}[${it.index.str()}]'
 		}
+		CastExpr {
+			return '${it.typname}(${it.expr.str()})'
+		}
 		else {
 			return '[unhandled expr type ${typeof(x)}]'
 		}
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 4059a07584..962c55cb10 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -676,7 +676,11 @@ fn (c mut Checker) stmt(node ast.Stmt) {
 	// c.expected_type = table.void_type
 	match mut node {
 		ast.AssertStmt {
-			c.expr(it.expr)
+			assert_type := c.expr(it.expr)
+			if assert_type != table.bool_type_idx {
+				atype_name := c.table.get_type_symbol(assert_type).name
+				c.error('assert can be used only with `bool` expressions, but found `${atype_name}` instead', it.pos)
+			}
 		}
 		ast.AssignStmt {
 			c.assign_stmt(mut it)
@@ -875,6 +879,7 @@ pub fn (c mut Checker) expr(node ast.Expr) table.Type {
 			if it.has_arg {
 				c.expr(it.arg)
 			}
+			it.typname = c.table.get_type_symbol(it.typ).name
 			return it.typ
 		}
 		ast.CallExpr {
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index d9d12947d6..bb0e23ac02 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -611,11 +611,10 @@ fn (g mut Gen) gen_assert_stmt(a ast.AssertStmt) {
 	if g.is_test {
 		g.writeln('{')
 		g.writeln('	g_test_oks++;')
-		g.writeln('	cb_assertion_ok( _STR("${mod_path}"), ${a.pos.line_nr}, _STR("assert ${s_assertion}"), _STR("${g.fn_decl.name}()") );')
-		// g.writeln('	println(_STR("OK ${mod_path}:${a.pos.line_nr}: fn ${g.fn_decl.name}(): assert $s_assertion"));')
+		g.writeln('	cb_assertion_ok( _STR("${mod_path}"), ${a.pos.line_nr+1}, _STR("assert ${s_assertion}"), _STR("${g.fn_decl.name}()") );')
 		g.writeln('}else{')
 		g.writeln('	g_test_fails++;')
-		g.writeln('	cb_assertion_failed( _STR("${mod_path}"), ${a.pos.line_nr}, _STR("assert ${s_assertion}"), _STR("${g.fn_decl.name}()") );')
+		g.writeln('	cb_assertion_failed( _STR("${mod_path}"), ${a.pos.line_nr+1}, _STR("assert ${s_assertion}"), _STR("${g.fn_decl.name}()") );')
 		g.writeln('	exit(1);')
 		g.writeln('	// TODO')
 		g.writeln('	// Maybe print all vars in a test function if it fails?')
@@ -623,7 +622,7 @@ fn (g mut Gen) gen_assert_stmt(a ast.AssertStmt) {
 		return
 	}
 	g.writeln('{}else{')
-	g.writeln('	eprintln(_STR("${mod_path}:${a.pos.line_nr}: FAIL: fn ${g.fn_decl.name}(): assert $s_assertion"));')
+	g.writeln('	eprintln(_STR("${mod_path}:${a.pos.line_nr+1}: FAIL: fn ${g.fn_decl.name}(): assert $s_assertion"));')
 	g.writeln('	exit(1);')
 	g.writeln('}')
 }
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index 0f05196ef4..e445183622 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -354,10 +354,11 @@ pub fn (p mut Parser) stmt() ast.Stmt {
 		}
 		.key_assert {
 			p.next()
+			assert_pos := p.tok.position()
 			expr := p.expr(0)
 			return ast.AssertStmt{
 				expr: expr
-				pos: p.tok.position()
+				pos: assert_pos
 			}
 		}
 		.key_mut, .key_static {
diff --git a/vlib/v/scanner/scanner.v b/vlib/v/scanner/scanner.v
index 75938068c8..12a1b57e62 100644
--- a/vlib/v/scanner/scanner.v
+++ b/vlib/v/scanner/scanner.v
@@ -724,6 +724,10 @@ pub fn (s mut Scanner) scan() token.Token {
 				s.ignore_line()
 				s.line_comment = s.text[start + 1..s.pos]
 				comment := s.line_comment.trim_space()
+				s.pos--
+				// fix line_nr, \n was read, and the comment is marked
+				// on the next line
+				s.line_nr--
 				if s.comments_mode == .parse_comments {
 					// Find out if this comment is on its own line (for vfmt)
 					mut is_separate_line_comment := true
@@ -735,10 +739,6 @@ pub fn (s mut Scanner) scan() token.Token {
 					if is_separate_line_comment {
 						comment = '|' + comment
 					}
-					s.pos--
-					// fix line_nr, \n was read, and the comment is marked
-					// on the next line
-					s.line_nr--
 					return s.new_token(.comment, comment)
 				}
 				// s.fgenln('// ${s.prev_tok.str()} "$s.line_comment"')
diff --git a/vlib/v/scanner/scanner_test.v b/vlib/v/scanner/scanner_test.v
index 73b596a29e..a94eee2a03 100644
--- a/vlib/v/scanner/scanner_test.v
+++ b/vlib/v/scanner/scanner_test.v
@@ -39,5 +39,5 @@ fn test_scan() {
 	assert e == 120.0
 	assert 1.23e+10 == 1.23e10
 	assert 1.23e+10 == 1.23e0010
-	assert -1.23e+10 == 1.23e0010 * -1.0
+	assert (-1.23e+10) == (1.23e0010 * -1.0)
 }