diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 7877ec2b45..e279e280ed 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -691,6 +691,7 @@ pub fn (mut c Checker) call_fn(call_expr mut ast.CallExpr) table.Type {
 	// look for function in format `mod.fn` or `fn` (main/builtin)
 	mut f := table.Fn{}
 	mut found := false
+	mut found_in_args := false
 	// try prefix with current module as it would have never gotten prefixed
 	if !fn_name.contains('.') && call_expr.mod !in ['builtin', 'main'] {
 		name_prefixed := '${call_expr.mod}.$fn_name'
@@ -717,6 +718,7 @@ pub fn (mut c Checker) call_fn(call_expr mut ast.CallExpr) table.Type {
 					info := vts.info as table.FnType
 					f = info.func
 					found = true
+					found_in_args = true
 				}
 			}
 		}
@@ -725,6 +727,12 @@ pub fn (mut c Checker) call_fn(call_expr mut ast.CallExpr) table.Type {
 		c.error('unknown function: $fn_name', call_expr.pos)
 		return table.void_type
 	}
+	if !found_in_args && call_expr.mod in ['builtin', 'main'] {
+		scope := c.file.scope.innermost(call_expr.pos.pos)
+		if _ := scope.find_var(fn_name) {
+			c.error('ambiguous call to: `$fn_name`, may refer to fn `$fn_name` or variable `$fn_name`', call_expr.pos)
+		}
+	}
 	call_expr.return_type = f.return_type
 	if f.return_type == table.void_type && f.ctdefine.len > 0 && f.ctdefine !in c.pref.compile_defines {
 		call_expr.should_be_skipped = true
diff --git a/vlib/v/checker/tests/ambiguous_function_call_a.out b/vlib/v/checker/tests/ambiguous_function_call_a.out
new file mode 100644
index 0000000000..18be4473e2
--- /dev/null
+++ b/vlib/v/checker/tests/ambiguous_function_call_a.out
@@ -0,0 +1,6 @@
+vlib/v/checker/tests/ambiguous_function_call_a.v:2:2: error: ambiguous call to: `foo`, may refer to fn `foo` or variable `foo` 
+    1| fn foo(foo int) {
+    2|     foo(foo + 1)
+           ~~~~~~~~~~~~
+    3| }
+    4|
diff --git a/vlib/v/checker/tests/ambiguous_function_call_a.v b/vlib/v/checker/tests/ambiguous_function_call_a.v
new file mode 100644
index 0000000000..e8ec08cdf7
--- /dev/null
+++ b/vlib/v/checker/tests/ambiguous_function_call_a.v
@@ -0,0 +1,7 @@
+fn foo(foo int) {
+	foo(foo + 1)
+}
+
+fn main() {
+	foo(5)
+}
diff --git a/vlib/v/checker/tests/ambiguous_function_call_a.vv b/vlib/v/checker/tests/ambiguous_function_call_a.vv
new file mode 100644
index 0000000000..e8ec08cdf7
--- /dev/null
+++ b/vlib/v/checker/tests/ambiguous_function_call_a.vv
@@ -0,0 +1,7 @@
+fn foo(foo int) {
+	foo(foo + 1)
+}
+
+fn main() {
+	foo(5)
+}
diff --git a/vlib/v/checker/tests/ambiguous_function_call_b.out b/vlib/v/checker/tests/ambiguous_function_call_b.out
new file mode 100644
index 0000000000..6d7417439e
--- /dev/null
+++ b/vlib/v/checker/tests/ambiguous_function_call_b.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/ambiguous_function_call_b.v:3:2: error: ambiguous call to: `foo`, may refer to fn `foo` or variable `foo` 
+    1| fn foo() {
+    2|     foo := 1
+    3|     foo(foo)
+           ~~~~~~~~
+    4| }
+    5|
diff --git a/vlib/v/checker/tests/ambiguous_function_call_b.v b/vlib/v/checker/tests/ambiguous_function_call_b.v
new file mode 100644
index 0000000000..c1dbab3b34
--- /dev/null
+++ b/vlib/v/checker/tests/ambiguous_function_call_b.v
@@ -0,0 +1,8 @@
+fn foo() {
+	foo := 1
+	foo(foo)
+}
+
+fn main() {
+	foo()
+}
diff --git a/vlib/v/checker/tests/ambiguous_function_call_b.vv b/vlib/v/checker/tests/ambiguous_function_call_b.vv
new file mode 100644
index 0000000000..c1dbab3b34
--- /dev/null
+++ b/vlib/v/checker/tests/ambiguous_function_call_b.vv
@@ -0,0 +1,8 @@
+fn foo() {
+	foo := 1
+	foo(foo)
+}
+
+fn main() {
+	foo()
+}