diff --git a/src/shellpop.zig b/src/shellpop.zig
index c9589b2..6c79651 100644
--- a/src/shellpop.zig
+++ b/src/shellpop.zig
@@ -43,22 +43,21 @@ const ShellPopcon = struct {
                 .blob = try BoundedArray(u8, MaxShells * MaxShellLen).init(0),
                 .indices = StringHashMap(u10).init(allocator),
             };
-            var offset: u10 = 0;
+            var fullOffset: u12 = 0;
             var idx: u10 = 0;
             while (idx < shells.len) {
                 const len = @intCast(u6, shells.get(idx).len);
                 try self.blob.appendSlice(shells.get(idx));
-                const ourShell = self.blob.constSlice()[offset .. offset + len];
+                const ourShell = self.blob.constSlice()[fullOffset .. fullOffset + len];
                 try self.indices.put(ourShell, idx);
                 self.index.set(idx, ShellIndex{
-                    .offset = offset >> 2,
+                    .offset = @intCast(u10, fullOffset >> 2),
                     .len = len,
                 });
-                offset += len;
 
                 // Padd padding to make offset divisible by 4.
-                const padding = (offset + 3) & ~@intCast(u10, 3);
-                offset += padding;
+                const padding = (fullOffset + 3) & ~@intCast(u12, 3);
+                fullOffset += len + padding;
                 try self.blob.appendNTimes(0, padding);
                 idx += 1;
             }
@@ -170,15 +169,15 @@ test "basic shellpopcon" {
     try testing.expectEqual(sections.getIndex(bash).?, 2);
     try testing.expectEqual(sections.getIndex(nobody), null);
 
-    const longIndex = sections.getIndex(long).?;
-    const start = sections.index.get(longIndex).offset << 2;
-    const end = start + sections.index.get(longIndex).len;
-    const gotLong = sections.blob.constSlice()[start..end];
+    const idx = sections.getIndex(zsh).?;
+    const start = sections.index.get(idx).offset << 2;
+    const end = start + sections.index.get(idx).len;
+    const got = sections.blob.constSlice()[start..end];
 
     const stderr = std.io.getStdErr().writer();
     try stderr.print("\n", .{});
 
-    try stderr.print("gotLong: {s}\n", .{gotLong});
-    try stderr.print("   long: {s}\n", .{long});
-    try testing.expectEqual(gotLong, long);
+    try stderr.print("gotLong: {s}\n", .{got});
+    try stderr.print("   long: {s}\n", .{zsh});
+    try testing.expectEqual(got, zsh);
 }