diff --git a/Changelog.md b/Changelog.md
index cd9859171..dd62f2df5 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -6,8 +6,11 @@ Features:
    path(s) of the supplied source file(s) is always trusted.
 
 Bugfixes:
- * Type system: Contract inheriting from base with unimplemented constructor should be abstract.
  * Assembly output: Implement missing AssemblyItem types.
+ * Compiler interface: Fix a bug where source indexes could be inconsistent between Solidity compiled
+   with different compilers (clang vs. gcc) or compiler settings. The bug was visible in AST
+   and source mappings.
+ * Type system: Contract inheriting from base with unimplemented constructor should be abstract.
 
 ### 0.4.10 (2017-03-15)
 
diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index 92b49cda5..6ea9ea783 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -406,8 +406,9 @@ vector<string> CompilerStack::sourceNames() const
 map<string, unsigned> CompilerStack::sourceIndices() const
 {
 	map<string, unsigned> indices;
+	unsigned index = 0;
 	for (auto const& s: m_sources)
-		indices[s.first] = indices.size();
+		indices[s.first] = index++;
 	return indices;
 }