diff --git a/cmd/vulnreport/main.go b/cmd/vulnreport/main.go
index e0eec04..9649506 100644
--- a/cmd/vulnreport/main.go
+++ b/cmd/vulnreport/main.go
@@ -13,6 +13,7 @@
 	"flag"
 	"fmt"
 	"go/build"
+	"go/types"
 	"log"
 	"os"
 	"os/exec"
@@ -24,6 +25,7 @@
 	"time"
 
 	"github.com/go-git/go-git/v5"
+	"golang.org/x/exp/slices"
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/vulndb/internal/cvelistrepo"
 	"golang.org/x/vulndb/internal/derrors"
@@ -278,9 +280,8 @@
 		if err != nil {
 			return false, err
 		}
-		if len(syms) > 0 {
+		if !slices.Equal(syms, r.Packages[i].DerivedSymbols) {
 			added = true
-			// Need to start from r because r.Packages is a slice of values.
 			r.Packages[i].DerivedSymbols = syms
 		}
 	}
@@ -348,13 +349,38 @@
 			return nil, fmt.Errorf("got module %v, expected %s", pm, module)
 		}
 	}
+
+	// Check to see that all symbols actually exist in the package.
+	// This should perhaps be a lint check, but lint doesn't
+	// load/typecheck packages at the moment, so do it here for now.
+	for _, sym := range p.Symbols {
+		if typ, method, ok := strings.Cut(sym, "."); ok {
+			n, ok := pkgs[0].Types.Scope().Lookup(typ).(*types.TypeName)
+			if !ok {
+				fmt.Fprintf(os.Stderr, "%v: type not found\n", typ)
+				continue
+			}
+			m, _, _ := types.LookupFieldOrMethod(n.Type(), true, pkgs[0].Types, method)
+			if m == nil {
+				fmt.Fprintf(os.Stderr, "%v: method not found\n", sym)
+			}
+		} else {
+			_, ok := pkgs[0].Types.Scope().Lookup(typ).(*types.Func)
+			if !ok {
+				fmt.Fprintf(os.Stderr, "%v: func not found\n", typ)
+			}
+		}
+	}
+
 	newsyms, err := exportedFunctions(pkgs, c)
 	if err != nil {
 		return nil, err
 	}
 	var newslice []string
 	for s := range newsyms {
-		newslice = append(newslice, s)
+		if !slices.Contains(p.Symbols, s) {
+			newslice = append(newslice, s)
+		}
 	}
 	sort.Strings(newslice)
 	return newslice, nil
diff --git a/go.mod b/go.mod
index 1450015..125eb78 100644
--- a/go.mod
+++ b/go.mod
@@ -17,7 +17,7 @@
 	github.com/client9/misspell v0.3.4
 	github.com/go-git/go-billy/v5 v5.3.1
 	github.com/go-git/go-git/v5 v5.4.2
-	github.com/google/go-cmp v0.5.7
+	github.com/google/go-cmp v0.5.8
 	github.com/google/go-github/v41 v41.0.0
 	github.com/google/safehtml v0.0.2
 	github.com/jba/templatecheck v0.6.0
@@ -25,6 +25,7 @@
 	go.opentelemetry.io/otel v1.4.0
 	go.opentelemetry.io/otel/metric v0.27.0
 	go.opentelemetry.io/otel/sdk v1.4.0
+	golang.org/x/exp v0.0.0-20220613132600-b0d781184e0d
 	golang.org/x/exp/event v0.0.0-20220218215828-6cf2b201936e
 	golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4
 	golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd
diff --git a/go.sum b/go.sum
index 2526759..4f32947 100644
--- a/go.sum
+++ b/go.sum
@@ -193,6 +193,8 @@
 github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.7 h1:81/ik6ipDQS2aGcBfIN5dHDB36BwrStyeAQquSYCV4o=
 github.com/google/go-cmp v0.5.7/go.mod h1:n+brtR0CgQNWTVd5ZUFpTBC8YFBDLK/h/bpaJ8/DtOE=
+github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
+github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-github/v41 v41.0.0 h1:HseJrM2JFf2vfiZJ8anY2hqBjdfY1Vlj/K27ueww4gg=
 github.com/google/go-github/v41 v41.0.0/go.mod h1:XgmCA5H323A9rtgExdTcnDkcqp6S30AVACCBDOonIxg=
 github.com/google/go-querystring v1.1.0 h1:AnCroh3fv4ZBgVIf1Iwtovgjaw/GiKJo8M8yD/fhyJ8=
@@ -355,6 +357,8 @@
 golang.org/x/exp v0.0.0-20200119233911-0405dc783f0a/go.mod h1:2RIsYlXP63K8oxa1u096TMicItID8zy7Y6sNkU49FU4=
 golang.org/x/exp v0.0.0-20200207192155-f17229e696bd/go.mod h1:J/WKrq2StrnmMY6+EHIKF9dgMWnmCNThgcyBT1FY9mM=
 golang.org/x/exp v0.0.0-20200224162631-6cc2880d07d6/go.mod h1:3jZMyOhIsHpP37uCMkUooju7aAi5cS1Q23tOzKc+0MU=
+golang.org/x/exp v0.0.0-20220613132600-b0d781184e0d h1:vtUKgx8dahOomfFzLREU8nSv25YHnTgLBn4rDnWZdU0=
+golang.org/x/exp v0.0.0-20220613132600-b0d781184e0d/go.mod h1:Kr81I6Kryrl9sr8s2FK3vxD90NdsKWRuOIl2O4CvYbA=
 golang.org/x/exp/event v0.0.0-20220218215828-6cf2b201936e h1:K2AuHMC+jaRTzAcivRwKOzjTZ1925Yx4xHMg07YoBQc=
 golang.org/x/exp/event v0.0.0-20220218215828-6cf2b201936e/go.mod h1:AVlZHjhWbW/3yOcmKMtJiObwBPJajBlUpQXRijFNrNc=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=