diff --git a/src/cmd/compile/internal/types2/lookup.go b/src/cmd/compile/internal/types2/lookup.go
index a05a5d6397d..8ed5ca837a0 100644
--- a/src/cmd/compile/internal/types2/lookup.go
+++ b/src/cmd/compile/internal/types2/lookup.go
@@ -52,7 +52,7 @@ func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 	// not have found it for T (see also issue 8590).
 	if t := asNamed(T); t != nil {
 		if p, _ := safeUnderlying(t).(*Pointer); p != nil {
-			obj, index, indirect = lookupFieldOrMethod(p, false, pkg, name)
+			obj, index, indirect = lookupFieldOrMethod(p, false, false, pkg, name)
 			if _, ok := obj.(*Func); ok {
 				return nil, nil, false
 			}
@@ -60,7 +60,7 @@ func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 		}
 	}
 
-	return lookupFieldOrMethod(T, addressable, pkg, name)
+	return lookupFieldOrMethod(T, addressable, false, pkg, name)
 }
 
 // TODO(gri) The named type consolidation and seen maps below must be
@@ -69,7 +69,9 @@ func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 //           indirectly via different packages.)
 
 // lookupFieldOrMethod should only be called by LookupFieldOrMethod and missingMethod.
-func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
+// If checkFold is true, the lookup for methods will include looking for any method
+// which case-folds to the same as 'name' (used for giving helpful error messages).
+func lookupFieldOrMethod(T Type, addressable, checkFold bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
 	// WARNING: The code in this function is extremely subtle - do not modify casually!
 
 	if name == "_" {
@@ -127,7 +129,7 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 				seen[named] = true
 
 				// look for a matching attached method
-				if i, m := lookupMethod(named.methods, pkg, name); m != nil {
+				if i, m := lookupMethodFold(named.methods, pkg, name, checkFold); m != nil {
 					// potential match
 					// caution: method may not have a proper signature yet
 					index = concat(e.index, i)
@@ -178,7 +180,7 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 
 			case *Interface:
 				// look for a matching method
-				if i, m := t.typeSet().LookupMethod(pkg, name); m != nil {
+				if i, m := lookupMethodFold(t.typeSet().methods, pkg, name, checkFold); m != nil {
 					assert(m.typ != nil)
 					index = concat(e.index, i)
 					if obj != nil || e.multiples {
@@ -189,7 +191,7 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 				}
 
 			case *TypeParam:
-				if i, m := t.iface().typeSet().LookupMethod(pkg, name); m != nil {
+				if i, m := lookupMethodFold(t.iface().typeSet().methods, pkg, name, checkFold); m != nil {
 					assert(m.typ != nil)
 					index = concat(e.index, i)
 					if obj != nil || e.multiples {
@@ -315,6 +317,7 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 				if !static {
 					continue
 				}
+				// We don't do any case-fold check if V is an interface.
 				return m, f
 			}
 
@@ -345,13 +348,20 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 
 	// A concrete type implements T if it implements all methods of T.
 	for _, m := range T.typeSet().methods {
-		// TODO(gri) should this be calling lookupFieldOrMethod instead (and why not)?
-		obj, _, _ := lookupFieldOrMethod(V, false, m.pkg, m.name)
+		// TODO(gri) should this be calling LookupFieldOrMethod instead (and why not)?
+		obj, _, _ := lookupFieldOrMethod(V, false, false, m.pkg, m.name)
 
 		// Check if *V implements this method of T.
 		if obj == nil {
 			ptr := NewPointer(V)
-			obj, _, _ = lookupFieldOrMethod(ptr, false, m.pkg, m.name)
+			obj, _, _ = lookupFieldOrMethod(ptr, false, false, m.pkg, m.name)
+			if obj != nil {
+				return m, obj.(*Func)
+			}
+			// If we didn't find the exact method (even with pointer
+			// receiver), look to see if there is a method that
+			// matches m.name with case-folding.
+			obj, _, _ := lookupFieldOrMethod(V, false, true, m.pkg, m.name)
 			if obj != nil {
 				return m, obj.(*Func)
 			}
@@ -410,7 +420,7 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 // where m is missing from V, but required by T. It puts the reason in parentheses,
 // and may include more have/want info after that. If non-nil, wrongType is a relevant
 // method that matches in some way. It may have the correct name, but wrong type, or
-// it may have a pointer receiver.
+// it may have a pointer receiver, or it may have the correct name except wrong case.
 func (check *Checker) missingMethodReason(V, T Type, m, wrongType *Func) string {
 	var r string
 	var mname string
@@ -527,3 +537,21 @@ func lookupMethod(methods []*Func, pkg *Package, name string) (int, *Func) {
 	}
 	return -1, nil
 }
+
+// lookupMethodFold is like lookupMethod, but if checkFold is true, it matches a method
+// name if the names are equal with case folding.
+func lookupMethodFold(methods []*Func, pkg *Package, name string, checkFold bool) (int, *Func) {
+	if name != "_" {
+		for i, m := range methods {
+			if m.name != name && !(checkFold && strings.EqualFold(m.name, name)) {
+				continue
+			}
+			// Use m.name, since we've already checked that m.name and
+			// name are equal with folding.
+			if m.sameId(pkg, m.name) {
+				return i, m
+			}
+		}
+	}
+	return -1, nil
+}
diff --git a/test/fixedbugs/issue48471.go b/test/fixedbugs/issue48471.go
index 0412d23b99c..2e00c87c6a9 100644
--- a/test/fixedbugs/issue48471.go
+++ b/test/fixedbugs/issue48471.go
@@ -29,11 +29,11 @@ func g() {
 	var i I
 	i = new(T)    // ERROR "cannot use new\(T\) \(.*type \*T\) as type I in assignment:\n\t\*T does not implement I \(missing M method\)"
 	i = I(new(T)) // ERROR "cannot convert new\(T\) \(.*type \*T\) to type I:\n\t\*T does not implement I \(missing M method\)"
-	i = new(T2)   // ERROR "cannot use new\(T2\) \(.*type \*T2\) as type I in assignment:\n\t\*T2 does not implement I \(missing M method\)"
+	i = new(T2)   // ERROR "cannot use new\(T2\) \(.*type \*T2\) as type I in assignment:\n\t\*T2 does not implement I \(missing M method\)\n\t\thave m\(int\)\n\t\twant M\(int\)"
 	i = new(T3)   // ERROR "cannot use new\(T3\) \(.*type \*T3\) as type I in assignment:\n\t\*T3 does not implement I \(wrong type for M method\)\n\t\thave M\(string\)\n\t\twant M\(int\)"
 	i = T4{}      // ERROR "cannot use T4\{\} \(.*type T4\) as type I in assignment:\n\tT4 does not implement I \(M method has pointer receiver\)"
 	i = new(I)    // ERROR "cannot use new\(I\) \(.*type \*I\) as type I in assignment:\n\t\*I does not implement I \(\*I is pointer to interface, not interface\)"
-	_ = i.(*T2)   // ERROR "impossible type assertion: i.\(\*T2\)\n\t\*T2 does not implement I \(missing M method\)"
+	_ = i.(*T2)   // ERROR "impossible type assertion: i.\(\*T2\)\n\t\*T2 does not implement I \(missing M method\)\n\t\thave m\(int\)\n\t\twant M\(int\)"
 	_ = i.(*T3)   // ERROR "impossible type assertion: i.\(\*T3\)\n\t\*T3 does not implement I \(wrong type for M method\)\n\t\thave M\(string\)\n\t\twant M\(int\)"
 	var t *T4
 	t = i // ERROR "cannot use i \(variable of type I\) as type \*T4 in assignment:\n\tneed type assertion"