diff --git a/source/dub/dependency.d b/source/dub/dependency.d
index a6ed09f..f9f666e 100644
--- a/source/dub/dependency.d
+++ b/source/dub/dependency.d
@@ -205,7 +205,7 @@
 	@property bool optional() const { return m_optional; }
 	@property void optional(bool optional) { m_optional = optional; }
 
-	@property Version version_() const { assert(m_versA == m_versB); return m_versA; }
+	@property Version version_() const { assert(m_versA == m_versB, "Dependency "~toString()~" is no exact version."); return m_versA; }
 	
 	string toString()
 	const {