diff --git a/src/install/extract_tarball.zig b/src/install/extract_tarball.zig
index acd9ac8dbd..b4cbe09026 100644
--- a/src/install/extract_tarball.zig
+++ b/src/install/extract_tarball.zig
@@ -11,13 +11,24 @@ url: strings.StringOrTinyString,
 package_manager: *PackageManager,
 
 pub inline fn run(this: *const ExtractTarball, log: *logger.Log, bytes: []const u8) !Install.ExtractData {
-    if (!this.skip_verify and this.integrity.tag.isSupported()) {
-        if (!this.integrity.verify(bytes)) {
+    if (!this.skip_verify) {
+        if (this.integrity.tag.isSupported()) {
+            if (!this.integrity.verify(bytes)) {
+                log.addErrorFmt(
+                    null,
+                    logger.Loc.Empty,
+                    bun.default_allocator,
+                    "Integrity check failed<r> for tarball: {s}",
+                    .{this.name.slice()},
+                ) catch unreachable;
+                return error.IntegrityCheckFailed;
+            }
+        } else if (this.resolution.tag == .npm) {
             log.addErrorFmt(
                 null,
                 logger.Loc.Empty,
                 bun.default_allocator,
-                "Integrity check failed<r> for tarball: {s}",
+                "Missing or unsupported integrity hash for tarball: {s}",
                 .{this.name.slice()},
             ) catch unreachable;
             return error.IntegrityCheckFailed;
diff --git a/src/install/lockfile/bun.lock.zig b/src/install/lockfile/bun.lock.zig
index de72aaf9a7..bef8b4577d 100644
--- a/src/install/lockfile/bun.lock.zig
+++ b/src/install/lockfile/bun.lock.zig
@@ -1868,6 +1868,10 @@ pub fn parseIntoBinaryLockfile(
                     };
 
                     pkg.meta.integrity = Integrity.parse(integrity_str);
+                    if (integrity_str.len > 0 and !pkg.meta.integrity.tag.isSupported()) {
+                        try log.addError(source, integrity_expr.loc, "Unsupported integrity hash algorithm");
+                        return error.InvalidPackageInfo;
+                    }
                 },
                 inline .git, .github => |tag| {
                     // .bun-tag
diff --git a/src/install/migration.zig b/src/install/migration.zig
index 3ca057ee54..05771c3949 100644
--- a/src/install/migration.zig
+++ b/src/install/migration.zig
@@ -541,13 +541,15 @@ pub fn migrateNPMLockfile(
                         .false;
                 } else .false,
 
-                .integrity = if (pkg.get("integrity")) |integrity|
-                    Integrity.parse(
-                        integrity.asString(this.allocator) orelse
-                            return error.InvalidNPMLockfile,
-                    )
-                else
-                    Integrity{},
+                .integrity = if (pkg.get("integrity")) |integrity| blk: {
+                    const integrity_str = integrity.asString(this.allocator) orelse
+                        return error.InvalidNPMLockfile;
+                    const parsed = Integrity.parse(integrity_str);
+                    if (integrity_str.len > 0 and !parsed.tag.isSupported()) {
+                        return error.InvalidNPMLockfile;
+                    }
+                    break :blk parsed;
+                } else Integrity{},
             },
             .bin = if (pkg.get("bin")) |bin| bin: {
                 // we already check these conditions during counting
diff --git a/src/install/pnpm.zig b/src/install/pnpm.zig
index 12070f593f..590c8aad58 100644
--- a/src/install/pnpm.zig
+++ b/src/install/pnpm.zig
@@ -613,6 +613,9 @@ pub fn migratePnpmLockfile(
                         };
 
                         pkg.meta.integrity = Integrity.parse(integrity_str);
+                        if (integrity_str.len > 0 and !pkg.meta.integrity.tag.isSupported()) {
+                            return invalidPnpmLockfile();
+                        }
                     }
                 }
 
diff --git a/src/install/yarn.zig b/src/install/yarn.zig
index 8bac336db0..c01672a653 100644
--- a/src/install/yarn.zig
+++ b/src/install/yarn.zig
@@ -997,10 +997,14 @@ pub fn migrateYarnLockfile(
                 } else .all,
                 .man_dir = String{},
                 .has_install_script = .false,
-                .integrity = if (entry.integrity) |integrity|
-                    Integrity.parse(integrity)
-                else
-                    Integrity{},
+                .integrity = if (entry.integrity) |integrity| blk: {
+                    const parsed = Integrity.parse(integrity);
+                    if (integrity.len > 0 and !parsed.tag.isSupported()) {
+                        try log.addError(null, logger.Loc.Empty, "Unsupported integrity hash algorithm in yarn.lock");
+                        return error.InvalidYarnLock;
+                    }
+                    break :blk parsed;
+                } else Integrity{},
             },
             .bin = Bin.init(),
             .scripts = .{},
diff --git a/test/cli/install/unsupported-integrity-hash.test.ts b/test/cli/install/unsupported-integrity-hash.test.ts
new file mode 100644
index 0000000000..780b4dde1c
--- /dev/null
+++ b/test/cli/install/unsupported-integrity-hash.test.ts
@@ -0,0 +1,126 @@
+import { expect, test } from "bun:test";
+import { bunEnv, bunExe, tempDir } from "harness";
+
+test("lockfile with unsupported integrity hash algorithm should fail", async () => {
+  using dir = tempDir("unsupported-integrity", {
+    "package.json": JSON.stringify({
+      name: "test-unsupported-integrity",
+      dependencies: {
+        "is-number": "7.0.0",
+      },
+    }),
+    "bun.lock": JSON.stringify(
+      {
+        lockfileVersion: 1,
+        configVersion: 1,
+        workspaces: {
+          "": {
+            name: "test-unsupported-integrity",
+            dependencies: {
+              "is-number": "7.0.0",
+            },
+          },
+        },
+        packages: {
+          "is-number": ["is-number@7.0.0", "", {}, "md5-AAAAAAAAAA=="],
+        },
+      },
+      null,
+      2,
+    ),
+  });
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "install", "--frozen-lockfile"],
+    env: bunEnv,
+    cwd: String(dir),
+    stderr: "pipe",
+    stdout: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  expect(stderr).toContain("Unsupported integrity hash algorithm");
+  expect(exitCode).toBe(1);
+});
+
+test("lockfile with valid integrity hash algorithm should succeed", async () => {
+  // First, create a real lockfile by installing
+  using dir = tempDir("valid-integrity", {
+    "package.json": JSON.stringify({
+      name: "test-valid-integrity",
+      dependencies: {
+        "is-number": "7.0.0",
+      },
+    }),
+  });
+
+  // Run install to generate a valid lockfile
+  await using installProc = Bun.spawn({
+    cmd: [bunExe(), "install"],
+    env: bunEnv,
+    cwd: String(dir),
+    stderr: "pipe",
+    stdout: "pipe",
+  });
+
+  const installExitCode = await installProc.exited;
+  expect(installExitCode).toBe(0);
+
+  // Now run with --frozen-lockfile to verify it works
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "install", "--frozen-lockfile"],
+    env: bunEnv,
+    cwd: String(dir),
+    stderr: "pipe",
+    stdout: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  expect(stderr).not.toContain("Unsupported integrity hash algorithm");
+  expect(exitCode).toBe(0);
+});
+
+test("lockfile with garbage integrity string should fail", async () => {
+  using dir = tempDir("garbage-integrity", {
+    "package.json": JSON.stringify({
+      name: "test-garbage-integrity",
+      dependencies: {
+        "is-number": "7.0.0",
+      },
+    }),
+    "bun.lock": JSON.stringify(
+      {
+        lockfileVersion: 1,
+        configVersion: 1,
+        workspaces: {
+          "": {
+            name: "test-garbage-integrity",
+            dependencies: {
+              "is-number": "7.0.0",
+            },
+          },
+        },
+        packages: {
+          "is-number": ["is-number@7.0.0", "", {}, "not-a-real-hash"],
+        },
+      },
+      null,
+      2,
+    ),
+  });
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "install", "--frozen-lockfile"],
+    env: bunEnv,
+    cwd: String(dir),
+    stderr: "pipe",
+    stdout: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  expect(stderr).toContain("Unsupported integrity hash algorithm");
+  expect(exitCode).toBe(1);
+});