diff --git a/compose/config/interpolation.py b/compose/config/interpolation.py
index cb841437..1b270b9e 100644
--- a/compose/config/interpolation.py
+++ b/compose/config/interpolation.py
@@ -72,7 +72,7 @@ def recursive_interpolate(obj, interpolator):
 
 
 class TemplateWithDefaults(Template):
-    idpattern = r'[_a-z][_a-z0-9]*(?::?-[_a-z0-9]+)?'
+    idpattern = r'[_a-z][_a-z0-9]*(?::?-[^}]+)?'
 
     # Modified from python2.7/string.py
     def substitute(self, mapping):
diff --git a/tests/unit/config/interpolation_test.py b/tests/unit/config/interpolation_test.py
index 22444495..fd40153d 100644
--- a/tests/unit/config/interpolation_test.py
+++ b/tests/unit/config/interpolation_test.py
@@ -113,6 +113,7 @@ def test_interpolate_with_value(defaults_interpolator):
 def test_interpolate_missing_with_default(defaults_interpolator):
     assert defaults_interpolator("ok ${missing:-def}") == "ok def"
     assert defaults_interpolator("ok ${missing-def}") == "ok def"
+    assert defaults_interpolator("ok ${BAR:-/non:-alphanumeric}") == "ok /non:-alphanumeric"
 
 
 def test_interpolate_with_empty_and_default_value(defaults_interpolator):