diff --git a/src/cmd/compile/internal/types2/resolver.go b/src/cmd/compile/internal/types2/resolver.go
index 61963cb043..5c64ecdfc8 100644
--- a/src/cmd/compile/internal/types2/resolver.go
+++ b/src/cmd/compile/internal/types2/resolver.go
@@ -179,8 +179,9 @@ func (check *Checker) importPackage(pos syntax.Pos, path, dir string) *Package {
 	// package should be complete or marked fake, but be cautious
 	if imp.complete || imp.fake {
 		check.impMap[key] = imp
-		// Once we've formatted an error message once, keep the pkgPathMap
-		// up-to-date on subsequent imports.
+		// Once we've formatted an error message, keep the pkgPathMap
+		// up-to-date on subsequent imports. It is used for package
+		// qualification in error messages.
 		if check.pkgPathMap != nil {
 			check.markImports(imp)
 		}
@@ -268,7 +269,7 @@ func (check *Checker) collectObjects() {
 				if s.LocalPkgName != nil {
 					name = s.LocalPkgName.Value
 					if path == "C" {
-						// match cmd/compile (not prescribed by spec)
+						// match 1.17 cmd/compile (not prescribed by spec)
 						check.error(s.LocalPkgName, `cannot rename import "C"`)
 						continue
 					}
@@ -295,8 +296,8 @@ func (check *Checker) collectObjects() {
 					check.recordImplicit(s, pkgName)
 				}
 
-				if path == "C" {
-					// match cmd/compile (not prescribed by spec)
+				if imp.fake {
+					// match 1.17 cmd/compile (not prescribed by spec)
 					pkgName.used = true
 				}
 
@@ -700,7 +701,7 @@ func (a inSourceOrder) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 
 // unusedImports checks for unused imports.
 func (check *Checker) unusedImports() {
-	// if function bodies are not checked, packages' uses are likely missing - don't check
+	// If function bodies are not checked, packages' uses are likely missing - don't check.
 	if check.conf.IgnoreFuncBodies {
 		return
 	}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue43109.go b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue43109.go
new file mode 100644
index 0000000000..a4533c9bf7
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue43109.go
@@ -0,0 +1,10 @@
+// Copyright 2022 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.
+
+// Ensure there is no "imported but not used" error
+// if a package wasn't imported in the first place.
+
+package p
+
+import . "/foo" // ERROR could not import \/foo
diff --git a/src/go/types/resolver.go b/src/go/types/resolver.go
index 9edf41bf3c..ae21c6d927 100644
--- a/src/go/types/resolver.go
+++ b/src/go/types/resolver.go
@@ -192,8 +192,9 @@ func (check *Checker) importPackage(at positioner, path, dir string) *Package {
 	// package should be complete or marked fake, but be cautious
 	if imp.complete || imp.fake {
 		check.impMap[key] = imp
-		// Once we've formatted an error message once, keep the pkgPathMap
-		// up-to-date on subsequent imports.
+		// Once we've formatted an error message, keep the pkgPathMap
+		// up-to-date on subsequent imports. It is used for package
+		// qualification in error messages.
 		if check.pkgPathMap != nil {
 			check.markImports(imp)
 		}
@@ -269,7 +270,7 @@ func (check *Checker) collectObjects() {
 				if d.spec.Name != nil {
 					name = d.spec.Name.Name
 					if path == "C" {
-						// match cmd/compile (not prescribed by spec)
+						// match 1.17 cmd/compile (not prescribed by spec)
 						check.errorf(d.spec.Name, _ImportCRenamed, `cannot rename import "C"`)
 						return
 					}
@@ -296,8 +297,8 @@ func (check *Checker) collectObjects() {
 					check.recordImplicit(d.spec, pkgName)
 				}
 
-				if path == "C" {
-					// match cmd/compile (not prescribed by spec)
+				if imp.fake {
+					// match 1.17 cmd/compile (not prescribed by spec)
 					pkgName.used = true
 				}
 
@@ -673,7 +674,7 @@ func (a inSourceOrder) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 
 // unusedImports checks for unused imports.
 func (check *Checker) unusedImports() {
-	// if function bodies are not checked, packages' uses are likely missing - don't check
+	// If function bodies are not checked, packages' uses are likely missing - don't check.
 	if check.conf.IgnoreFuncBodies {
 		return
 	}
diff --git a/src/go/types/testdata/fixedbugs/issue43109.go b/src/go/types/testdata/fixedbugs/issue43109.go
new file mode 100644
index 0000000000..a4533c9bf7
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue43109.go
@@ -0,0 +1,10 @@
+// Copyright 2022 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.
+
+// Ensure there is no "imported but not used" error
+// if a package wasn't imported in the first place.
+
+package p
+
+import . "/foo" // ERROR could not import \/foo