diff --git a/spec/compiler/formatter/formatter_spec.cr b/spec/compiler/formatter/formatter_spec.cr
index 0a7695f4ead6..b8e0d524ac79 100644
--- a/spec/compiler/formatter/formatter_spec.cr
+++ b/spec/compiler/formatter/formatter_spec.cr
@@ -2857,6 +2857,14 @@ describe Crystal::Formatter do
     def baz; end
     CRYSTAL
 
+  # 15180
+  assert_format <<-CRYSTAL
+    x = uninitialized Foo
+    {% begin %}
+      x = foo(x)
+    {% end %}
+    CRYSTAL
+
   # CVE-2021-42574
   describe "Unicode bi-directional control characters" do
     ['\u202A', '\u202B', '\u202C', '\u202D', '\u202E', '\u2066', '\u2067', '\u2068', '\u2069'].each do |char|
diff --git a/src/compiler/crystal/tools/formatter.cr b/src/compiler/crystal/tools/formatter.cr
index 9c036faa4b9e..dcd7be66df08 100644
--- a/src/compiler/crystal/tools/formatter.cr
+++ b/src/compiler/crystal/tools/formatter.cr
@@ -3657,7 +3657,11 @@ module Crystal
     end
 
     def visit(node : UninitializedVar)
-      accept node.var
+      var = node.var
+
+      @vars.last.add var.name if var.is_a?(Var)
+
+      accept var
       skip_space_or_newline
       write_token " ", :OP_EQ, " "
       skip_space_or_newline