diff --git a/src/nlpmacros.jl b/src/nlpmacros.jl
index ee547d5fd7c..56769efa7e4 100644
--- a/src/nlpmacros.jl
+++ b/src/nlpmacros.jl
@@ -16,9 +16,18 @@ function parseNLExpr(m, x, tapevar, parent, values)
             code = :(let; end)
             block = code.args[1]
             @assert isexpr(block, :block)
-            haskey(univariate_operator_to_id,x.args[1]) || error("Unrecognized function $(x.args[1]) used in nonlinear expression.")
-            operatorid = univariate_operator_to_id[x.args[1]]
-            push!(block.args, :(push!($tapevar, NodeData(CALLUNIVAR, $operatorid, $parent))))
+            if haskey(univariate_operator_to_id,x.args[1])
+                operatorid = univariate_operator_to_id[x.args[1]]
+                push!(block.args, :(push!($tapevar, NodeData(CALLUNIVAR, $operatorid, $parent))))
+            else
+                opname = quot(x.args[1])
+                errorstring = "Unrecognized function $opname used in nonlinear expression."
+                lookupcode = quote
+                    haskey(univariate_operator_to_id,$opname) || error($errorstring)
+                    operatorid = univariate_operator_to_id[$opname]
+                end
+                push!(block.args, :($lookupcode; push!($tapevar, NodeData(CALLUNIVAR, operatorid, $parent))))
+            end
             parentvar = gensym()
             push!(block.args, :($parentvar = length($tapevar)))
             push!(block.args, parseNLExpr(m, x.args[2], tapevar, parentvar, values))
@@ -27,10 +36,19 @@ function parseNLExpr(m, x, tapevar, parent, values)
             code = :(let; end)
             block = code.args[1]
             @assert isexpr(block, :block)
-            haskey(operator_to_id,x.args[1]) || error("Unrecognized function $(x.args[1]) used in nonlinear expression.")
-            operatorid = operator_to_id[x.args[1]]
+            if haskey(operator_to_id,x.args[1]) # fast compile-time lookup
+                operatorid = operator_to_id[x.args[1]]
+                push!(block.args, :(push!($tapevar, NodeData(CALL, $operatorid, $parent))))
+            else # could be user defined
+                opname = quot(x.args[1])
+                errorstring = "Unrecognized function $opname used in nonlinear expression."
+                lookupcode = quote
+                    haskey(operator_to_id,$opname) || error($errorstring)
+                    operatorid = operator_to_id[$opname]
+                end
+                push!(block.args, :($lookupcode; push!($tapevar, NodeData(CALL, operatorid, $parent))))
+            end
             parentvar = gensym()
-            push!(block.args, :(push!($tapevar, NodeData(CALL, $operatorid, $parent))))
             push!(block.args, :($parentvar = length($tapevar)))
             for i in 1:length(x.args)-1
                 push!(block.args, parseNLExpr(m, x.args[i+1], tapevar, parentvar, values))
diff --git a/test/nonlinear.jl b/test/nonlinear.jl
index 96264b583b0..01a7d8bca91 100644
--- a/test/nonlinear.jl
+++ b/test/nonlinear.jl
@@ -646,14 +646,16 @@ mysquare(x) = x^2
 function myf(x,y)
     return (x-1)^2+(y-2)^2
 end
-registerNLFunction(:myf, 2, myf, autodiff=true)
-registerNLFunction(:myf_2, 2, myf, (g,x,y) -> (g[1] = 2(x-1); g[2] = 2(y-2)))
-registerNLFunction(:mysquare, 1, mysquare, autodiff=true)
-registerNLFunction(:mysquare_2, 1, mysquare, x-> 2x, autodiff=true)
-registerNLFunction(:mysquare_3, 1, mysquare, x-> 2x, x -> 2.0)
+
 
 if length(convex_nlp_solvers) > 0
     facts("[nonlinear] User-defined functions") do
+        registerNLFunction(:myf, 2, myf, autodiff=true)
+        registerNLFunction(:myf_2, 2, myf, (g,x,y) -> (g[1] = 2(x-1); g[2] = 2(y-2)))
+        registerNLFunction(:mysquare, 1, mysquare, autodiff=true)
+        registerNLFunction(:mysquare_2, 1, mysquare, x-> 2x, autodiff=true)
+        registerNLFunction(:mysquare_3, 1, mysquare, x-> 2x, x -> 2.0)
+
         m = Model(solver=convex_nlp_solvers[1])
 
         @defVar(m, x[1:2] >= 0.5)