diff --git a/src/containsAggregate.zig b/src/containsAggregate.zig
index b931fcbffc9a8a7df22d249595a3cf5e2749494d..6dadf2948e0b3380228f2ba0514ace211a9abaae 100644
--- a/src/containsAggregate.zig
+++ b/src/containsAggregate.zig
@@ -1,14 +1,10 @@
 const std = @import("std");
 const string = []const u8;
 const extras = @import("./lib.zig");
+const indexOfAggregate = extras.indexOfAggregate;
 
 pub fn containsAggregate(comptime T: type, haystack: []const T, needle: T) bool {
-    for (haystack) |item| {
-        if (T.eql(item, needle)) {
-            return true;
-        }
-    }
-    return false;
+    return indexOfAggregate(T, haystack, needle) != null;
 }
 
 test {
diff --git a/src/indexOfAggregate.zig b/src/indexOfAggregate.zig
new file mode 100644
index 0000000000000000000000000000000000000000..46b03823e3b243be20bee32cefe3996aa4876403
--- /dev/null
+++ b/src/indexOfAggregate.zig
@@ -0,0 +1,35 @@
+const std = @import("std");
+const string = []const u8;
+const extras = @import("./lib.zig");
+
+pub fn indexOfAggregate(comptime T: type, haystack: []const T, needle: T) ?usize {
+    for (haystack, 0..) |item, i| {
+        if (T.eql(item, needle)) {
+            return i;
+        }
+    }
+    return null;
+}
+
+test {
+    const S = struct {
+        a: u8,
+
+        fn eql(this: @This(), other: @This()) bool {
+            return this.a == other.a;
+        }
+    };
+    const data = [_]S{
+        .{ .a = 8 },
+        .{ .a = 6 },
+        .{ .a = 7 },
+        .{ .a = 2 },
+        .{ .a = 4 },
+        .{ .a = 1 },
+        .{ .a = 9 },
+        .{ .a = 3 },
+        .{ .a = 5 },
+    };
+    try std.testing.expect(indexOfAggregate(S, &data, .{ .a = 4 }) == 4);
+    try std.testing.expect(indexOfAggregate(S, &data, .{ .a = 0 }) == null);
+}
diff --git a/src/lib.zig b/src/lib.zig
index a9881c735d52514a36f718dbcb8c816ee9572cc0..cdb650202ccba376dacbcb97a17f2e2cd07884c7 100644
--- a/src/lib.zig
+++ b/src/lib.zig
@@ -88,6 +88,7 @@ pub const Pointee = @import("./Pointee.zig").Pointee;
 pub const compareFnSlice = @import("./compareFnSlice.zig").compareFnSlice;
 pub const sumLen = @import("./sumLen.zig").sumLen;
 pub const splitScalarN = @import("./splitScalarN.zig").splitScalarN;
+pub const indexOfAggregate = @import("./indexOfAggregate.zig").indexOfAggregate;
 
 test {
     _ = @import("reduceNumber.zig");
@@ -165,4 +166,5 @@ test {
     _ = @import("compareFnSlice.zig");
     _ = @import("sumLen.zig");
     _ = @import("splitScalarN.zig");
+    _ = @import("indexOfAggregate.zig");
 }