diff --git a/compiler/optimizer.go b/compiler/optimizer.go
index b194e388..b1b81d39 100644
--- a/compiler/optimizer.go
+++ b/compiler/optimizer.go
@@ -219,6 +219,16 @@ func (c *Compiler) doesEscape(value llvm.Value) bool {
 			// Call only escapes when the (pointer) parameter is not marked
 			// "nocapture". This flag means that the parameter does not escape
 			// the give function.
+			if use.CalledValue().IsAFunction() != nilValue {
+				if use.CalledValue().IsDeclaration() {
+					// Kind of dirty: assume external functions don't let
+					// pointers escape.
+					// TODO: introduce //go:noescape that sets the 'nocapture'
+					// flag on each input parameter.
+					println("declaration:", use.CalledValue().Name())
+					continue
+				}
+			}
 			if !c.hasFlag(use, value, "nocapture") {
 				return true
 			}