diff --git a/src/script_opt/CPP/Driver.cc b/src/script_opt/CPP/Driver.cc
index a93b0f603b..2cecb4923c 100644
--- a/src/script_opt/CPP/Driver.cc
+++ b/src/script_opt/CPP/Driver.cc
@@ -77,8 +77,9 @@ void CPPCompile::Compile(bool report_uncompilable)
 			continue;
 			}
 
-		if ( is_when_lambda(f) )
+		if ( is_lambda(f) || is_when_lambda(f) )
 			{
+			// We deal with these separately.
 			func.SetSkip(true);
 			continue;
 			}
diff --git a/src/script_opt/ScriptOpt.cc b/src/script_opt/ScriptOpt.cc
index f01ae2db1f..1b085a9dc2 100644
--- a/src/script_opt/ScriptOpt.cc
+++ b/src/script_opt/ScriptOpt.cc
@@ -58,6 +58,11 @@ void analyze_when_lambda(LambdaExpr* l)
 	when_lambdas.insert(l->PrimaryFunc().get());
 	}
 
+bool is_lambda(const ScriptFunc* f)
+	{
+	return lambdas.count(f) > 0;
+	}
+
 bool is_when_lambda(const ScriptFunc* f)
 	{
 	return when_lambdas.count(f) > 0;
diff --git a/src/script_opt/ScriptOpt.h b/src/script_opt/ScriptOpt.h
index 0e8e0ed09f..1a6145f243 100644
--- a/src/script_opt/ScriptOpt.h
+++ b/src/script_opt/ScriptOpt.h
@@ -174,7 +174,8 @@ extern void analyze_lambda(LambdaExpr* f);
 // has already been called.
 extern void analyze_when_lambda(LambdaExpr* f);
 
-// Whether a given script function is a "when" lambda.
+// Whether a given script function is a lambda or (separately) a "when" lambda.
+extern bool is_lambda(const ScriptFunc* f);
 extern bool is_when_lambda(const ScriptFunc* f);
 
 // Analyze the given top-level statement(s) for optimization.  Returns