diff --git a/vulncheck/binary.go b/vulncheck/binary.go
index 65ea431..66721c5 100644
--- a/vulncheck/binary.go
+++ b/vulncheck/binary.go
@@ -7,17 +7,18 @@
 import (
 	"io"
 
+	"golang.org/x/tools/go/packages"
 	"golang.org/x/vuln/vulncheck/internal/binscan"
 )
 
 // Binary detects presence of vulnerable symbols in exe. The
 // imports, require, and call graph are all unavailable (nil).
 func Binary(exe io.ReaderAt, cfg *Config) (*Result, error) {
-	modules, packageSymbols, err := binscan.ExtractPackagesAndSymbols(exe)
+	mods, packageSymbols, err := binscan.ExtractPackagesAndSymbols(exe)
 	if err != nil {
 		return nil, err
 	}
-	modVulns, err := fetchVulnerabilities(cfg.Client, modules)
+	modVulns, err := fetchVulnerabilities(cfg.Client, convertModules(mods))
 	if err != nil {
 		return nil, err
 	}
@@ -45,3 +46,22 @@
 	}
 	return result, nil
 }
+
+func convertModules(mods []*packages.Module) []*Module {
+	vmods := make([]*Module, len(mods))
+	// TODO(github.com/golang/go/issues/50030): should we share unique
+	// modules? Not needed nowas module info is not returned by Binary.
+	for i, mod := range mods {
+		vmods[i] = &Module{
+			Path:    mod.Path,
+			Version: mod.Version,
+		}
+		if mod.Replace != nil {
+			vmods[i].Replace = &Module{
+				Path:    mod.Replace.Path,
+				Version: mod.Replace.Version,
+			}
+		}
+	}
+	return vmods
+}
diff --git a/vulncheck/fetch.go b/vulncheck/fetch.go
index 5cef708..9cbb214 100644
--- a/vulncheck/fetch.go
+++ b/vulncheck/fetch.go
@@ -11,12 +11,11 @@
 	"path/filepath"
 	"strings"
 
-	"golang.org/x/tools/go/packages"
 	"golang.org/x/vulndb/client"
 )
 
 // modKey creates a unique string identifier for mod.
-func modKey(mod *packages.Module) string {
+func modKey(mod *Module) string {
 	if mod == nil {
 		return ""
 	}
@@ -25,12 +24,12 @@
 
 // extractModules collects modules in `pkgs` up to uniqueness of
 // module path and version.
-func extractModules(pkgs []*packages.Package) []*packages.Module {
-	modMap := map[string]*packages.Module{}
+func extractModules(pkgs []*Package) []*Module {
+	modMap := map[string]*Module{}
 
-	seen := map[*packages.Package]bool{}
-	var extract func(*packages.Package, map[string]*packages.Module)
-	extract = func(pkg *packages.Package, modMap map[string]*packages.Module) {
+	seen := map[*Package]bool{}
+	var extract func(*Package, map[string]*Module)
+	extract = func(pkg *Package, modMap map[string]*Module) {
 		if pkg == nil || seen[pkg] {
 			return
 		}
@@ -50,7 +49,7 @@
 		extract(pkg, modMap)
 	}
 
-	modules := []*packages.Module{}
+	modules := []*Module{}
 	for _, mod := range modMap {
 		modules = append(modules, mod)
 	}
@@ -58,7 +57,7 @@
 }
 
 // fetchVulnerabilities fetches vulnerabilities that affect the supplied modules.
-func fetchVulnerabilities(client client.Client, modules []*packages.Module) (moduleVulnerabilities, error) {
+func fetchVulnerabilities(client client.Client, modules []*Module) (moduleVulnerabilities, error) {
 	mv := moduleVulnerabilities{}
 	for _, mod := range modules {
 		modPath := mod.Path
@@ -91,7 +90,7 @@
 // loading local vulnerabilities in testing.
 var fetchingInTesting bool = false
 
-func isLocal(mod *packages.Module) bool {
+func isLocal(mod *Module) bool {
 	if fetchingInTesting {
 		return false
 	}
@@ -101,7 +100,6 @@
 	}
 	return !strings.HasPrefix(modDir, modCacheDirectory())
 }
-
 func modCacheDirectory() string {
 	var modCacheDir string
 	// TODO: define modCacheDir using something similar to cmd/go/internal/cfg.GOMODCACHE?
diff --git a/vulncheck/fetch_test.go b/vulncheck/fetch_test.go
index a60edee..252282f 100644
--- a/vulncheck/fetch_test.go
+++ b/vulncheck/fetch_test.go
@@ -8,7 +8,6 @@
 	"reflect"
 	"testing"
 
-	"golang.org/x/tools/go/packages"
 	"golang.org/x/vulndb/osv"
 )
 
@@ -22,11 +21,11 @@
 		},
 	}
 
-	mv, err := fetchVulnerabilities(mc, []*packages.Module{
+	mv, err := fetchVulnerabilities(mc, []*Module{
 		{Path: "example.mod/a", Dir: modCacheDirectory(), Version: "v1.0.0"},
 		{Path: "example.mod/b", Dir: modCacheDirectory(), Version: "v1.0.4"},
-		{Path: "example.mod/c", Replace: &packages.Module{Path: "example.mod/d", Dir: modCacheDirectory(), Version: "v1.0.0"}, Version: "v2.0.0"},
-		{Path: "example.mod/e", Replace: &packages.Module{Path: "../local/example.mod/d", Dir: modCacheDirectory(), Version: "v1.0.1"}, Version: "v2.1.0"},
+		{Path: "example.mod/c", Replace: &Module{Path: "example.mod/d", Dir: modCacheDirectory(), Version: "v1.0.0"}, Version: "v2.0.0"},
+		{Path: "example.mod/e", Replace: &Module{Path: "../local/example.mod/d", Dir: modCacheDirectory(), Version: "v1.0.1"}, Version: "v2.1.0"},
 	})
 	if err != nil {
 		t.Fatalf("FetchVulnerabilities failed: %s", err)
@@ -34,19 +33,19 @@
 
 	expected := moduleVulnerabilities{
 		{
-			mod: &packages.Module{Path: "example.mod/a", Dir: modCacheDirectory(), Version: "v1.0.0"},
+			mod: &Module{Path: "example.mod/a", Dir: modCacheDirectory(), Version: "v1.0.0"},
 			vulns: []*osv.Entry{
 				{ID: "a", Affected: []osv.Affected{{Package: osv.Package{Name: "example.mod/a"}, Ranges: osv.Affects{{Type: osv.TypeSemver, Events: []osv.RangeEvent{{Fixed: "2.0.0"}}}}}}},
 			},
 		},
 		{
-			mod: &packages.Module{Path: "example.mod/b", Dir: modCacheDirectory(), Version: "v1.0.4"},
+			mod: &Module{Path: "example.mod/b", Dir: modCacheDirectory(), Version: "v1.0.4"},
 			vulns: []*osv.Entry{
 				{ID: "b", Affected: []osv.Affected{{Package: osv.Package{Name: "example.mod/b"}, Ranges: osv.Affects{{Type: osv.TypeSemver, Events: []osv.RangeEvent{{Fixed: "1.1.1"}}}}}}},
 			},
 		},
 		{
-			mod: &packages.Module{Path: "example.mod/c", Replace: &packages.Module{Path: "example.mod/d", Dir: modCacheDirectory(), Version: "v1.0.0"}, Version: "v2.0.0"},
+			mod: &Module{Path: "example.mod/c", Replace: &Module{Path: "example.mod/d", Dir: modCacheDirectory(), Version: "v1.0.0"}, Version: "v2.0.0"},
 			vulns: []*osv.Entry{
 				{ID: "c", Affected: []osv.Affected{{Package: osv.Package{Name: "example.mod/d"}, Ranges: osv.Affects{{Type: osv.TypeSemver, Events: []osv.RangeEvent{{Fixed: "2.0.0"}}}}}}},
 			},
diff --git a/vulncheck/source.go b/vulncheck/source.go
index 4ec495c..cac1ac3 100644
--- a/vulncheck/source.go
+++ b/vulncheck/source.go
@@ -6,9 +6,7 @@
 
 import (
 	"golang.org/x/tools/go/callgraph"
-	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/go/ssa"
-	"golang.org/x/tools/go/ssa/ssautil"
 	"golang.org/x/vulndb/osv"
 )
 
@@ -19,7 +17,7 @@
 //    package that has some known vulnerabilities
 //  - call graph leading to the use of a known vulnerable function
 //    or method
-func Source(pkgs []*packages.Package, cfg *Config) (*Result, error) {
+func Source(pkgs []*Package, cfg *Config) (*Result, error) {
 	modVulns, err := fetchVulnerabilities(cfg.Client, extractModules(pkgs))
 	if err != nil {
 		return nil, err
@@ -37,8 +35,7 @@
 		return result, nil
 	}
 
-	prog, ssaPkgs := ssautil.AllPackages(pkgs, 0)
-	prog.Build()
+	prog, ssaPkgs := buildSSA(pkgs)
 	entries := entryPoints(ssaPkgs)
 	cg := callGraph(prog, entries)
 	vulnCallGraphSlice(entries, modVulns, cg, result)
@@ -57,12 +54,12 @@
 // vulnPkgModSlice computes the slice of pkgs imports and requires graph
 // leading to imports/requires of vulnerable packages/modules in modVulns
 // and stores the computed slices to result.
-func vulnPkgModSlice(pkgs []*packages.Package, modVulns moduleVulnerabilities, result *Result) {
+func vulnPkgModSlice(pkgs []*Package, modVulns moduleVulnerabilities, result *Result) {
 	// analyzedPkgs contains information on packages analyzed thus far.
 	// If a package is mapped to nil, this means it has been visited
 	// but it does not lead to a vulnerable imports. Otherwise, a
 	// visited package is mapped to Imports package node.
-	analyzedPkgs := make(map[*packages.Package]*PkgNode)
+	analyzedPkgs := make(map[*Package]*PkgNode)
 	for _, pkg := range pkgs {
 		// Top level packages that lead to vulnerable imports are
 		// stored as result.Imports graph entry points.
@@ -80,7 +77,7 @@
 // a package with known vulnerabilities. If that is the case, populates result.Imports
 // graph with this reachability information and returns the result.Imports package
 // node for pkg. Otherwise, returns nil.
-func vulnImportSlice(pkg *packages.Package, modVulns moduleVulnerabilities, result *Result, analyzed map[*packages.Package]*PkgNode) *PkgNode {
+func vulnImportSlice(pkg *Package, modVulns moduleVulnerabilities, result *Result, analyzed map[*Package]*PkgNode) *PkgNode {
 	if pn, ok := analyzed[pkg]; ok {
 		return pn
 	}
diff --git a/vulncheck/source_test.go b/vulncheck/source_test.go
index df0e272..2cf7cb1 100644
--- a/vulncheck/source_test.go
+++ b/vulncheck/source_test.go
@@ -109,7 +109,7 @@
 		Client:      testClient,
 		ImportsOnly: true,
 	}
-	result, err := Source(pkgs, cfg)
+	result, err := Source(Convert(pkgs), cfg)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -345,7 +345,7 @@
 	cfg := &Config{
 		Client: testClient,
 	}
-	result, err := Source(pkgs, cfg)
+	result, err := Source(Convert(pkgs), cfg)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/vulncheck/utils.go b/vulncheck/utils.go
index eea2078..d120f56 100644
--- a/vulncheck/utils.go
+++ b/vulncheck/utils.go
@@ -19,6 +19,41 @@
 	"golang.org/x/tools/go/ssa"
 )
 
+// buildSSA creates an ssa representation for pkgs. Returns
+// the ssa program encapsulating the packages and top level
+// ssa packages corresponding to pkgs.
+func buildSSA(pkgs []*Package) (*ssa.Program, []*ssa.Package) {
+	prog := ssa.NewProgram(token.NewFileSet(), ssa.BuilderMode(0))
+
+	imports := make(map[*Package]*ssa.Package)
+	var createImports func([]*Package)
+	createImports = func(pkgs []*Package) {
+		for _, p := range pkgs {
+			if _, ok := imports[p]; !ok {
+				i := prog.CreatePackage(p.Pkg, p.Syntax, p.TypesInfo, true)
+				imports[p] = i
+				createImports(p.Imports)
+			}
+		}
+	}
+
+	for _, tp := range pkgs {
+		createImports(tp.Imports)
+	}
+
+	var ssaPkgs []*ssa.Package
+	for _, tp := range pkgs {
+		if sp, ok := imports[tp]; ok {
+			ssaPkgs = append(ssaPkgs, sp)
+		} else {
+			sp := prog.CreatePackage(tp.Pkg, tp.Syntax, tp.TypesInfo, false)
+			ssaPkgs = append(ssaPkgs, sp)
+		}
+	}
+	prog.Build()
+	return prog, ssaPkgs
+}
+
 // callGraph builds a call graph of prog based on VTA analysis.
 func callGraph(prog *ssa.Program, entries []*ssa.Function) *callgraph.Graph {
 	entrySlice := make(map[*ssa.Function]bool)
diff --git a/vulncheck/vulncheck.go b/vulncheck/vulncheck.go
index 38b6c2c..86bd89b 100644
--- a/vulncheck/vulncheck.go
+++ b/vulncheck/vulncheck.go
@@ -236,7 +236,7 @@
 	ImportedBy []int
 
 	// pkg is used for connecting package node to module and call graph nodes.
-	pkg *packages.Package
+	pkg *Package
 }
 
 // moduleVulnerabilities is an internal structure for
@@ -246,7 +246,7 @@
 
 // modVulns groups vulnerabilities per module.
 type modVulns struct {
-	mod   *packages.Module
+	mod   *Module
 	vulns []*osv.Entry
 }
 
diff --git a/vulncheck/vulncheck_test.go b/vulncheck/vulncheck_test.go
index d68a1ee..076c458 100644
--- a/vulncheck/vulncheck_test.go
+++ b/vulncheck/vulncheck_test.go
@@ -9,7 +9,6 @@
 	"reflect"
 	"testing"
 
-	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/go/packages/packagestest"
 	"golang.org/x/vulndb/osv"
 )
@@ -17,7 +16,7 @@
 func TestFilterVulns(t *testing.T) {
 	mv := moduleVulnerabilities{
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/a",
 				Version: "v1.0.0",
 			},
@@ -32,7 +31,7 @@
 			},
 		},
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/b",
 				Version: "v1.0.0",
 			},
@@ -44,7 +43,7 @@
 			},
 		},
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path: "example.mod/c",
 			},
 			vulns: []*osv.Entry{
@@ -54,7 +53,7 @@
 			},
 		},
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/d",
 				Version: "v1.2.0",
 			},
@@ -69,7 +68,7 @@
 
 	expected := moduleVulnerabilities{
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/a",
 				Version: "v1.0.0",
 			},
@@ -79,7 +78,7 @@
 			},
 		},
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/b",
 				Version: "v1.0.0",
 			},
@@ -89,12 +88,12 @@
 			},
 		},
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path: "example.mod/c",
 			},
 		},
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/d",
 				Version: "v1.2.0",
 			},
@@ -113,7 +112,7 @@
 func TestVulnsForPackage(t *testing.T) {
 	mv := moduleVulnerabilities{
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/a",
 				Version: "v1.0.0",
 			},
@@ -122,7 +121,7 @@
 			},
 		},
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/a/b",
 				Version: "v1.0.0",
 			},
@@ -131,7 +130,7 @@
 			},
 		},
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/d",
 				Version: "v0.0.1",
 			},
@@ -154,7 +153,7 @@
 func TestVulnsForPackageReplaced(t *testing.T) {
 	mv := moduleVulnerabilities{
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/a",
 				Version: "v1.0.0",
 			},
@@ -163,9 +162,9 @@
 			},
 		},
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path: "example.mod/a/b",
-				Replace: &packages.Module{
+				Replace: &Module{
 					Path: "example.mod/b",
 				},
 				Version: "v1.0.0",
@@ -189,7 +188,7 @@
 func TestVulnsForSymbol(t *testing.T) {
 	mv := moduleVulnerabilities{
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/a",
 				Version: "v1.0.0",
 			},
@@ -198,7 +197,7 @@
 			},
 		},
 		{
-			mod: &packages.Module{
+			mod: &Module{
 				Path:    "example.mod/a/b",
 				Version: "v1.0.0",
 			},