diff --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -2428,6 +2428,13 @@
   if (allowForwardReference && ImplicitlyTypeForwardRef(symbol)) {
     return;
   }
+  if (const auto *entity{symbol.detailsIf<EntityDetails>()};
+      entity && entity->isDummy()) {
+    // Dummy argument, no declaration or reference; if it turns
+    // out to be a subroutine, it's fine, and if it is a function
+    // or object, it'll be caught later.
+    return;
+  }
   if (!context().HasError(symbol)) {
     Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
     context().SetError(symbol);
diff --git a/flang/test/Semantics/implicit13.f90 b/flang/test/Semantics/implicit13.f90
new file mode 100644
--- /dev/null
+++ b/flang/test/Semantics/implicit13.f90
@@ -0,0 +1,9 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+!ERROR: No explicit type declared for 'func'
+!ERROR: No explicit type declared for 'obj'
+subroutine implicit_none(func, sub, obj)
+  implicit none
+  call sub ! ok
+  print *, func()
+  print *, obj
+end