diff --git a/lib/Semantics/resolve-names.cpp b/lib/Semantics/resolve-names.cpp
index 398f45c..f69e770 100644
--- a/lib/Semantics/resolve-names.cpp
+++ b/lib/Semantics/resolve-names.cpp
@@ -3248,7 +3248,12 @@
       if (!specific) {
         specific =
             &currScope().MakeSymbol(name.source, Attrs{}, SubprogramDetails{});
-        details->set_specific(Resolve(name, *specific));
+        if (details->derivedType()) {
+          // A specific procedure with the same name as a derived type
+          SayAlreadyDeclared(name, *details->derivedType());
+        } else {
+          details->set_specific(Resolve(name, *specific));
+        }
       } else if (isGeneric()) {
         SayAlreadyDeclared(name, *specific);
       }
diff --git a/test/Semantics/resolve18.f90 b/test/Semantics/resolve18.f90
index 94b217e..dd92145 100644
--- a/test/Semantics/resolve18.f90
+++ b/test/Semantics/resolve18.f90
@@ -63,6 +63,15 @@
   function foo(x)
   end
 end
+module m4c
+  type :: foo
+  end type
+  interface foo
+    !ERROR: 'foo' is already declared in this scoping unit
+    real function foo()
+    end function foo
+  end interface foo
+end
 
 ! Use associating a name that is a generic and a derived type
 module m5a