diff --git a/workflows/affy_workflow.py b/workflows/affy_workflow.py
index c60a433..a89071d 100644
--- a/workflows/affy_workflow.py
+++ b/workflows/affy_workflow.py
@@ -161,9 +161,7 @@ Example: Y-N, M-F""" % ", ".join(data.get_categories()))
 
         rpy.r.assign("expr", affy.asarray())
         silent_eval("fit <- lmFit(expr, design)")
-        # FIXME: might be a case for code injection...
-        string = "contrast.matrix <- makeContrasts(%s, levels=design)" % response
-        silent_eval(string)
+        silent_eval("contrast.matrix <- makeContrasts(%s, levels=design)" % response)
         silent_eval("fit2 <- contrasts.fit(fit, contrast.matrix)")
         silent_eval("fit2 <- eBayes(fit2)")
         coeff = rpy.r("fit2$coefficients")