diff --git a/src/cmd/compile/internal/gc/esc.go b/src/cmd/compile/internal/gc/esc.go
index 5992c07215..e97b06c8e5 100644
--- a/src/cmd/compile/internal/gc/esc.go
+++ b/src/cmd/compile/internal/gc/esc.go
@@ -477,6 +477,10 @@ func escAnalyze(all []*Node, recursive bool) {
 	for _, n := range all {
 		if n.Op == ODCLFUNC {
 			n.Esc = EscFuncPlanned
+			if Debug['m'] > 3 {
+				Dump("escAnalyze", n)
+			}
+
 		}
 	}
 
@@ -1682,7 +1686,10 @@ func (e *EscState) escflows(dst, src *Node, why *EscStep) {
 	}
 
 	// Don't bother building a graph for scalars.
-	if src.Type != nil && !haspointers(src.Type) {
+	if src.Type != nil && !haspointers(src.Type) && !isReflectHeaderDataField(src) {
+		if Debug['m'] > 3 {
+			fmt.Printf("%v::NOT flows:: %S <- %S\n", linestr(lineno), dst, src)
+		}
 		return
 	}
 
diff --git a/test/fixedbugs/issue19743.go b/test/fixedbugs/issue19743.go
new file mode 100644
index 0000000000..e57b19c8d0
--- /dev/null
+++ b/test/fixedbugs/issue19743.go
@@ -0,0 +1,31 @@
+// errorcheck -0 -m -l
+
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package foo
+
+// Escape analysis needs to treat the uintptr-typed reflect.*Header fields as pointers.
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+type immutableBytes []byte
+
+// Bug was failure to leak param b.
+func toString(b immutableBytes) string { // ERROR "leaking param: b$"
+	var s string
+	if len(b) == 0 {
+		return s
+	}
+
+	strHeader := (*reflect.StringHeader)(unsafe.Pointer(&s))         // ERROR "toString &s does not escape$"
+	strHeader.Data = (*reflect.SliceHeader)(unsafe.Pointer(&b)).Data // ERROR "toString &b does not escape$"
+
+	l := len(b)
+	strHeader.Len = l
+	return s
+}