diff --git a/src/cmd/compile/internal/ssa/regalloc.go b/src/cmd/compile/internal/ssa/regalloc.go
index a0257f3064..861cf7e011 100644
--- a/src/cmd/compile/internal/ssa/regalloc.go
+++ b/src/cmd/compile/internal/ssa/regalloc.go
@@ -1810,7 +1810,7 @@ func (s *regAllocState) regalloc(f *Func) {
 			if regspec.clobbersArg0 {
 				s.freeReg(register(s.f.getHome(args[0].ID).(*Register).num))
 			}
-			if regspec.clobbersArg1 {
+			if regspec.clobbersArg1 && !(regspec.clobbersArg0 && s.f.getHome(args[0].ID) == s.f.getHome(args[1].ID)) {
 				s.freeReg(register(s.f.getHome(args[1].ID).(*Register).num))
 			}
 
diff --git a/test/fixedbugs/issue77604.go b/test/fixedbugs/issue77604.go
new file mode 100644
index 0000000000..62857f57f0
--- /dev/null
+++ b/test/fixedbugs/issue77604.go
@@ -0,0 +1,20 @@
+// compile
+
+// Copyright 2026 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.
+
+// Issue 77604: compiler crash when source and destination
+// of copy are the same address.
+
+package p
+
+type T struct {
+	a [192]byte
+}
+
+func f(x *T) {
+	i := any(x)
+	y := i.(*T)
+	*y = *x
+}