diff --git a/src/install/semver.zig b/src/install/semver.zig
index f2bec912d2..0582e7b1b1 100644
--- a/src/install/semver.zig
+++ b/src/install/semver.zig
@@ -1199,7 +1199,8 @@ pub const Version = extern struct {
                     }
 
                     if (i < input.len and switch (input[i]) {
-                        '.' => true,
+                        // `.` is expected only if there are remaining core version numbers
+                        '.' => part_i != 3,
                         else => false,
                     }) {
                         i += 1;
diff --git a/test/cli/install/registry/bun-install-registry.test.ts b/test/cli/install/registry/bun-install-registry.test.ts
index baf97e11d1..9efbb93495 100644
--- a/test/cli/install/registry/bun-install-registry.test.ts
+++ b/test/cli/install/registry/bun-install-registry.test.ts
@@ -6421,6 +6421,10 @@ const prereleaseFailTests = [
       title: "greater than or equal to highest prerelease + 1",
       depVersion: ">=5.0.0-alpha.154",
     },
+    {
+      title: "`.` instead of `-` should fail",
+      depVersion: "5.0.0.alpha.150",
+    },
   ],
   // prereleases-4 has one version
   // - 2.0.0-pre.0