diff --git a/src/cmd/compile/internal/gc/bexport.go b/src/cmd/compile/internal/gc/bexport.go
index 0d4997ccfc..d0b1804eb6 100644
--- a/src/cmd/compile/internal/gc/bexport.go
+++ b/src/cmd/compile/internal/gc/bexport.go
@@ -464,19 +464,22 @@ func (p *exporter) markType(t *types.Type) {
 	}
 
 	// Recursively mark any types that can be produced given a
-	// value of type t: dereferencing a pointer; indexing an
-	// array, slice, or map; receiving from a channel; accessing a
-	// struct field or interface method; or calling a function.
+	// value of type t: dereferencing a pointer; indexing or
+	// iterating over an array, slice, or map; receiving from a
+	// channel; accessing a struct field or interface method; or
+	// calling a function.
 	//
-	// Notably, we don't mark map key or function parameter types,
-	// because the user already needs some way to construct values
-	// of those types.
-	//
-	// It's not critical for correctness that this algorithm is
-	// perfect. Worst case, we might miss opportunities to inline
-	// some function calls in downstream packages.
+	// Notably, we don't mark function parameter types, because
+	// the user already needs some way to construct values of
+	// those types.
 	switch t.Etype {
-	case TPTR32, TPTR64, TARRAY, TSLICE, TCHAN, TMAP:
+	case TPTR32, TPTR64, TARRAY, TSLICE, TCHAN:
+		// TODO(mdempsky): Skip marking element type for
+		// send-only channels?
+		p.markType(t.Elem())
+
+	case TMAP:
+		p.markType(t.Key())
 		p.markType(t.Elem())
 
 	case TSTRUCT:
diff --git a/test/fixedbugs/issue26341.dir/a.go b/test/fixedbugs/issue26341.dir/a.go
new file mode 100644
index 0000000000..4fd23c796b
--- /dev/null
+++ b/test/fixedbugs/issue26341.dir/a.go
@@ -0,0 +1,11 @@
+// Copyright 2018 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 a
+
+type k int
+
+func (k) F() {}
+
+type M map[k]int
diff --git a/test/fixedbugs/issue26341.dir/b.go b/test/fixedbugs/issue26341.dir/b.go
new file mode 100644
index 0000000000..30b8c25a5c
--- /dev/null
+++ b/test/fixedbugs/issue26341.dir/b.go
@@ -0,0 +1,13 @@
+// Copyright 2018 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 b
+
+import "./a"
+
+func f() {
+	for k := range (a.M{}) {
+		k.F()
+	}
+}
diff --git a/test/fixedbugs/issue26341.go b/test/fixedbugs/issue26341.go
new file mode 100644
index 0000000000..128cf9d06a
--- /dev/null
+++ b/test/fixedbugs/issue26341.go
@@ -0,0 +1,7 @@
+// compiledir
+
+// Copyright 2018 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 ignored