diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index a32590e003d..01a5c435aab 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -1223,8 +1223,10 @@ assignop(Type *src, Type *dst, char **why)
 	
 	// 2. src and dst have identical underlying types
 	// and either src or dst is not a named type or
-	// both are interface types.
-	if(eqtype(src->orig, dst->orig) && (src->sym == S || dst->sym == S || src->etype == TINTER))
+	// both are empty interface types.
+	// For assignable but different non-empty interface types,
+	// we want to recompute the itab.
+	if(eqtype(src->orig, dst->orig) && (src->sym == S || dst->sym == S || isnilinter(src)))
 		return OCONVNOP;
 
 	// 3. dst is an interface type and src implements dst.
diff --git a/test/cmp.go b/test/cmp.go
index 9ac0ebe79d3..80d1bf699fd 100644
--- a/test/cmp.go
+++ b/test/cmp.go
@@ -35,6 +35,10 @@ func istrue(b bool) {
 
 type T *int
 
+type X int
+
+func (X) x() {}
+
 func main() {
 	var a []int
 	var b map[string]int
@@ -129,6 +133,44 @@ func main() {
 		panic("bad m[c]")
 	}
 
+	// interface comparisons (issue 7207)
+	{
+		type I1 interface {
+			x()
+		}
+		type I2 interface {
+			x()
+		}
+		a1 := I1(X(0))
+		b1 := I1(X(1))
+		a2 := I2(X(0))
+		b2 := I2(X(1))
+		a3 := I1(a2)
+		a4 := I2(a1)
+		var e interface{} = X(0)
+		a5 := e.(I1)
+		a6 := e.(I2)
+		isfalse(a1 == b1)
+		isfalse(a1 == b2)
+		isfalse(a2 == b1)
+		isfalse(a2 == b2)
+		istrue(a1 == a2)
+		istrue(a1 == a3)
+		istrue(a1 == a4)
+		istrue(a1 == a5)
+		istrue(a1 == a6)
+		istrue(a2 == a3)
+		istrue(a2 == a4)
+		istrue(a2 == a5)
+		istrue(a2 == a6)
+		istrue(a3 == a4)
+		istrue(a3 == a5)
+		istrue(a3 == a6)
+		istrue(a4 == a5)
+		istrue(a4 == a6)
+		istrue(a5 == a6)
+	}
+
 	// non-interface comparisons
 	{
 		c := make(chan int)