diff --git a/cmd/v/v.v b/cmd/v/v.v
index 9f80568fc2..3bb826efb7 100644
--- a/cmd/v/v.v
+++ b/cmd/v/v.v
@@ -143,6 +143,9 @@ fn parse_args(args []string) (&pref.Preferences, string) {
 			'-shared' {
 				res.is_shared = true
 			}
+			'--enable-globals' {
+				res.enable_globals = true
+			}
 			'-autofree' {
 				res.autofree = true
 			}
diff --git a/vlib/v/checker/checker_test.v b/vlib/v/checker/checker_test.v
index 5309c39da3..626a2b2eb5 100644
--- a/vlib/v/checker/checker_test.v
+++ b/vlib/v/checker/checker_test.v
@@ -1,10 +1,6 @@
 import os
 import term
 
-fn clean_line_endings(s string) string {
-	return s.trim_space().replace(' \n', '\n').replace(' \r\n', '\n').replace('\r\n', '\n').trim('\n')
-}
-
 fn test_all() {
 	mut total_errors := 0
 	vexe := os.getenv('VEXE')
@@ -21,35 +17,45 @@ fn test_all() {
 	}
 	tests.sort()
 	for test in tests {
-		path := os.join_path(dir, test).replace('\\', '/')
-		program := path.replace('.vv', '.v')
-		print(program + ' ')
-		os.cp(path, program) or {
-			panic(err)
-		}
-		// -prod so that warn are errors
-		res := os.exec('$vexe -prod $program') or {
-			panic(err)
-		}
-		mut expected := os.read_file(program.replace('.v', '') + '.out') or {
-			panic(err)
-		}
-		expected = clean_line_endings(expected)
-		found := clean_line_endings(res.output)
-		if expected != found {
-			println(term.red('FAIL'))
-			println('============')
-			println('expected:')
-			println(expected)
-			println('============')
-			println('found:')
-			println(found)
-			println('============\n')
-			total_errors++
-		} else {
-			println(term.green('OK'))
-			os.rm( program )
-		}
+		// -prod so that warns are errors
+		total_errors += check_path(vexe, dir, test, '-prod', '.out')
 	}
+	total_errors += check_path(vexe, dir, 'globals_error.vv', '--enable-globals run', '.run.out')
 	assert total_errors == 0
 }
+
+fn check_path(vexe, dir, test, voptions, result_extension string) int {
+	path := os.join_path(dir, test).replace('\\', '/')
+	program := path.replace('.vv', '.v')
+	print(program + ' ')
+	os.cp(path, program) or {
+		panic(err)
+	}
+	res := os.exec('$vexe $voptions $program') or {
+		panic(err)
+	}
+	mut expected := os.read_file(program.replace('.v', '') + result_extension) or {
+		panic(err)
+	}
+	expected = clean_line_endings(expected)
+	found := clean_line_endings(res.output)
+	if expected != found {
+		println(term.red('FAIL'))
+		println('============')
+		println('expected:')
+		println(expected)
+		println('============')
+		println('found:')
+		println(found)
+		println('============\n')
+		return 1
+	} else {
+		println(term.green('OK'))
+		os.rm(program)
+	}
+	return 0
+}
+
+fn clean_line_endings(s string) string {
+	return s.trim_space().replace(' \n', '\n').replace(' \r\n', '\n').replace('\r\n', '\n').trim('\n')
+}
diff --git a/vlib/v/checker/tests/globals_error.out b/vlib/v/checker/tests/globals_error.out
new file mode 100644
index 0000000000..4903c540a0
--- /dev/null
+++ b/vlib/v/checker/tests/globals_error.out
@@ -0,0 +1,6 @@
+vlib/v/checker/tests/globals_error.v:2:1: error: use `v --enable-globals ...` to enable globals
+    1 |
+    2 | __global rfcnt int
+      | ~~~~~~~~
+    3 |
+    4 | fn abc(){
diff --git a/vlib/v/checker/tests/globals_error.run.out b/vlib/v/checker/tests/globals_error.run.out
new file mode 100644
index 0000000000..525f325b33
--- /dev/null
+++ b/vlib/v/checker/tests/globals_error.run.out
@@ -0,0 +1 @@
+rfcnt: 2
diff --git a/vlib/v/checker/tests/globals_error.vv b/vlib/v/checker/tests/globals_error.vv
new file mode 100644
index 0000000000..1b35df827f
--- /dev/null
+++ b/vlib/v/checker/tests/globals_error.vv
@@ -0,0 +1,12 @@
+
+__global rfcnt int
+
+fn abc(){
+	rfcnt = 2
+}
+
+fn main(){
+	rfcnt = 1
+	abc()
+	println('rfcnt: $rfcnt')
+}
diff --git a/vlib/v/pref/default.v b/vlib/v/pref/default.v
index 9c775ffefb..f02892ec93 100644
--- a/vlib/v/pref/default.v
+++ b/vlib/v/pref/default.v
@@ -70,7 +70,6 @@ pub fn (mut p Preferences) fill_with_defaults() {
 			}
 		}
 	}
-	p.enable_globals = false
 }
 
 fn default_c_compiler() string {