diff --git a/pkg/sentry/build.zig b/pkg/sentry/build.zig
index 131dea1ca..2873e49c4 100644
--- a/pkg/sentry/build.zig
+++ b/pkg/sentry/build.zig
@@ -32,6 +32,21 @@ pub fn build(b: *std.Build) !void {
     var flags = std.ArrayList([]const u8).init(b.allocator);
     defer flags.deinit();
     try flags.appendSlice(&.{});
+    if (target.result.os.tag == .windows) {
+        try flags.appendSlice(&.{
+            "-DSENTRY_WITH_UNWINDER_DBGHELP",
+        });
+    } else {
+        try flags.appendSlice(&.{
+            "-DSENTRY_WITH_UNWINDER_LIBBACKTRACE",
+        });
+    }
+    switch (backend) {
+        .crashpad => try flags.append("-DSENTRY_BACKEND_CRASHPAD"),
+        .breakpad => try flags.append("-DSENTRY_BACKEND_BREAKPAD"),
+        .inproc => try flags.append("-DSENTRY_BACKEND_INPROC"),
+        .none => {},
+    }
 
     lib.addCSourceFiles(.{
         .root = upstream.path(""),
@@ -50,7 +65,7 @@ pub fn build(b: *std.Build) !void {
         });
     }
 
-    // Symbolizer
+    // Symbolizer + Unwinder
     if (target.result.os.tag == .windows) {
         lib.addCSourceFiles(.{
             .root = upstream.path(""),
@@ -69,6 +84,7 @@ pub fn build(b: *std.Build) !void {
                 "src/sentry_unix_pageallocator.c",
                 "src/path/sentry_path_unix.c",
                 "src/symbolizer/sentry_symbolizer_unix.c",
+                "src/unwinder/sentry_unwinder_libbacktrace.c",
             },
             .flags = flags.items,
         });
diff --git a/src/Surface.zig b/src/Surface.zig
index a0f668e6e..aa9ac17df 100644
--- a/src/Surface.zig
+++ b/src/Surface.zig
@@ -1333,6 +1333,8 @@ pub fn keyCallback(
     self: *Surface,
     event: input.KeyEvent,
 ) !InputEffect {
+    // To test crash reporting
+    if (true) @panic("OH NO");
     // log.debug("text keyCallback event={}", .{event});
 
     // Setup our inspector event if we have an inspector.
diff --git a/src/sentry.zig b/src/sentry.zig
index 86567fbad..bf3015798 100644
--- a/src/sentry.zig
+++ b/src/sentry.zig
@@ -82,7 +82,7 @@ pub const Transport = struct {
     /// Implementation of send but we can use Zig errors.
     fn sendInternal(envelope: *sentry.Envelope) !void {
         // If our envelope doesn't have an event then we don't do anything.
-        if (envelope.event() == null) return;
+        // TODO: figure out how to not encode empty envelopes.
 
         var arena = std.heap.ArenaAllocator.init(state.alloc);
         defer arena.deinit();