diff --git a/internal/lsp/lsp_test.go b/internal/lsp/lsp_test.go
index 866b093e4f..686c1cee05 100644
--- a/internal/lsp/lsp_test.go
+++ b/internal/lsp/lsp_test.go
@@ -466,16 +466,30 @@ func (r *runner) Implementation(t *testing.T, spn span.Span, m tests.Implementat
 	if len(locs) != len(m.Implementations) {
 		t.Fatalf("got %d locations for implementation, expected %d", len(locs), len(m.Implementations))
 	}
+
+	var results []span.Span
 	for i := range locs {
 		locURI := span.NewURI(locs[i].URI)
 		lm, err := r.data.Mapper(locURI)
 		if err != nil {
 			t.Fatal(err)
 		}
-		if imp, err := lm.Span(locs[i]); err != nil {
+		imp, err := lm.Span(locs[i])
+		if err != nil {
 			t.Fatalf("failed for %v: %v", locs[i], err)
-		} else if imp != m.Implementations[i] {
-			t.Errorf("for %dth implementation of %v got %v want %v", i, m.Src, imp, m.Implementations[i])
+		}
+		results = append(results, imp)
+	}
+	// Sort results and expected to make tests deterministic.
+	sort.SliceStable(results, func(i, j int) bool {
+		return span.Compare(results[i], results[j]) == -1
+	})
+	sort.SliceStable(m.Implementations, func(i, j int) bool {
+		return span.Compare(m.Implementations[i], m.Implementations[j]) == -1
+	})
+	for i := range results {
+		if results[i] != m.Implementations[i] {
+			t.Errorf("for %dth implementation of %v got %v want %v", i, m.Src, results[i], m.Implementations[i])
 		}
 	}
 }
diff --git a/internal/lsp/source/implementation.go b/internal/lsp/source/implementation.go
index 7702b8e2c6..61e80cfb9c 100644
--- a/internal/lsp/source/implementation.go
+++ b/internal/lsp/source/implementation.go
@@ -12,8 +12,8 @@ package source
 import (
 	"context"
 	"fmt"
+	"go/token"
 	"go/types"
-	"sort"
 
 	"golang.org/x/tools/go/types/typeutil"
 	"golang.org/x/tools/internal/lsp/protocol"
@@ -27,10 +27,16 @@ func (i *IdentifierInfo) Implementation(ctx context.Context) ([]protocol.Locatio
 
 	var objs []types.Object
 	pkgs := map[types.Object]Package{}
+	// To ensure that we get one object per position, the seen map tracks object positions.
+	var seen map[token.Pos]bool
 
 	if res.toMethod != nil {
+		seen = make(map[token.Pos]bool, len(res.toMethod))
 		// If we looked up a method, results are in toMethod.
 		for _, s := range res.toMethod {
+			if seen[s.Obj().Pos()] {
+				continue
+			}
 			// Determine package of receiver.
 			recv := s.Recv()
 			if p, ok := recv.(*types.Pointer); ok {
@@ -42,8 +48,10 @@ func (i *IdentifierInfo) Implementation(ctx context.Context) ([]protocol.Locatio
 			}
 			// Add object to objs.
 			objs = append(objs, s.Obj())
+			seen[s.Obj().Pos()] = true
 		}
 	} else {
+		seen = make(map[token.Pos]bool, len(res.to))
 		// Otherwise, the results are in to.
 		for _, t := range res.to {
 			// We'll provide implementations that are named types and pointers to named types.
@@ -51,15 +59,18 @@ func (i *IdentifierInfo) Implementation(ctx context.Context) ([]protocol.Locatio
 				t = p.Elem()
 			}
 			if n, ok := t.(*types.Named); ok {
+				if seen[n.Obj().Pos()] {
+					continue
+				}
 				pkg := res.pkgs[n]
-				objs = append(objs, n.Obj())
 				pkgs[n.Obj()] = pkg
+				objs = append(objs, n.Obj())
+				seen[n.Obj().Pos()] = true
 			}
 		}
 	}
 
 	var locations []protocol.Location
-
 	for _, obj := range objs {
 		pkg := pkgs[obj]
 		if pkgs[obj] == nil || len(pkg.CompiledGoFiles()) == 0 {
@@ -86,9 +97,9 @@ func (i *IdentifierInfo) Implementation(ctx context.Context) ([]protocol.Locatio
 			Range: decRange,
 		})
 	}
-
 	return locations, nil
 }
+
 func (i *IdentifierInfo) implementations(ctx context.Context) (implementsResult, error) {
 	var T types.Type
 	var method *types.Func
@@ -174,12 +185,6 @@ func (i *IdentifierInfo) implementations(ctx context.Context) (implementsResult,
 			}
 		}
 	}
-
-	// Sort types (arbitrarily) to ensure test determinism.
-	sort.Sort(typesByString(to))
-	sort.Sort(typesByString(from))
-	sort.Sort(typesByString(fromPtr))
-
 	var toMethod []*types.Selection // contain nils
 	if method != nil {
 		for _, t := range to {
@@ -187,7 +192,6 @@ func (i *IdentifierInfo) implementations(ctx context.Context) (implementsResult,
 				types.NewMethodSet(t).Lookup(method.Pkg(), method.Name()))
 		}
 	}
-
 	return implementsResult{pkgs, to, from, fromPtr, toMethod}, nil
 }
 
@@ -199,9 +203,3 @@ type implementsResult struct {
 	fromPtr  []types.Type // named interfaces assignable only from *T
 	toMethod []*types.Selection
 }
-
-type typesByString []types.Type
-
-func (p typesByString) Len() int           { return len(p) }
-func (p typesByString) Less(i, j int) bool { return p[i].String() < p[j].String() }
-func (p typesByString) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
diff --git a/internal/lsp/source/source_test.go b/internal/lsp/source/source_test.go
index c9a56fa099..cda30b4db7 100644
--- a/internal/lsp/source/source_test.go
+++ b/internal/lsp/source/source_test.go
@@ -573,16 +573,29 @@ func (r *runner) Implementation(t *testing.T, spn span.Span, m tests.Implementat
 	if len(locs) != len(m.Implementations) {
 		t.Fatalf("got %d locations for implementation, expected %d", len(locs), len(m.Implementations))
 	}
+	var results []span.Span
 	for i := range locs {
 		locURI := span.NewURI(locs[i].URI)
 		lm, err := r.data.Mapper(locURI)
 		if err != nil {
 			t.Fatal(err)
 		}
-		if imp, err := lm.Span(locs[i]); err != nil {
+		imp, err := lm.Span(locs[i])
+		if err != nil {
 			t.Fatalf("failed for %v: %v", locs[i], err)
-		} else if imp != m.Implementations[i] {
-			t.Errorf("for %dth implementation of %v got %v want %v", i, m.Src, imp, m.Implementations[i])
+		}
+		results = append(results, imp)
+	}
+	// Sort results and expected to make tests deterministic.
+	sort.SliceStable(results, func(i, j int) bool {
+		return span.Compare(results[i], results[j]) == -1
+	})
+	sort.SliceStable(m.Implementations, func(i, j int) bool {
+		return span.Compare(m.Implementations[i], m.Implementations[j]) == -1
+	})
+	for i := range results {
+		if results[i] != m.Implementations[i] {
+			t.Errorf("for %dth implementation of %v got %v want %v", i, m.Src, results[i], m.Implementations[i])
 		}
 	}
 }