diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index bbc94e031..dfa7629da 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -332,12 +332,19 @@ bool CompilerStack::analyze()
 					if (!resolver.resolveNamesAndTypes(*node))
 						return false;
 					if (ContractDefinition* contract = dynamic_cast<ContractDefinition*>(node.get()))
+					{
 						// Note that we now reference contracts by their fully qualified names, and
-						// thus contracts can only conflict if declared in the same source file.  This
-						// already causes a double-declaration error elsewhere, so we do not report
-						// an error here and instead silently drop any additional contracts we find.
+						// thus contracts can only conflict if declared in the same source file. This
+						// should already cause a double-declaration error elsewhere.
 						if (m_contracts.find(contract->fullyQualifiedName()) == m_contracts.end())
 							m_contracts[contract->fullyQualifiedName()].contract = contract;
+						else
+							solAssert(
+								m_errorReporter.hasErrors(),
+								"Contract already present (name clash?), but no error was reported."
+							);
+					}
+
 				}
 
 		// Next, we check inheritance, overrides, function collisions and other things at