diff --git a/src/GraphControl/Control/Grapher.cpp b/src/GraphControl/Control/Grapher.cpp
index 20c16fad2..980488bf1 100644
--- a/src/GraphControl/Control/Grapher.cpp
+++ b/src/GraphControl/Control/Grapher.cpp
@@ -373,7 +373,7 @@ namespace GraphControl
                 request += s_getGraphClosingTags;
             }
 
-            if (graphExpression = m_solver->ParseInput(request, m_errorCode, m_errorType))
+            if (graphExpression == m_solver->ParseInput(request, m_errorCode, m_errorType))
             {
                 initResult = TryInitializeGraph(keepCurrentView, graphExpression.get());