diff --git a/hw/xquartz/darwin.c b/hw/xquartz/darwin.c
index 1abe2534fe..ae758d7c44 100644
--- a/hw/xquartz/darwin.c
+++ b/hw/xquartz/darwin.c
@@ -519,9 +519,10 @@ InitInput(int argc, char **argv)
     /* We need to really have rules... or something... */
     XkbSetRulesDflts(&rmlvo);
 
-    assert(Success == AllocDevicePair(serverClient, "xquartz virtual",
-                                      &darwinPointer, &darwinKeyboard,
-                                      DarwinMouseProc, DarwinKeybdProc, FALSE));
+    if (Success != AllocDevicePair(serverClient, "xquartz virtual",
+                                    &darwinPointer, &darwinKeyboard,
+                                    DarwinMouseProc, DarwinKeybdProc, FALSE))
+        FatalError("Failed to allocate xquartz virtual device pair\n");
 
     /* here's the snippet from the current gdk sources:
        if (!strcmp (tmp_name, "pointer"))
@@ -538,15 +539,18 @@ InitInput(int argc, char **argv)
      */
 
     darwinTabletStylus = AddInputDevice(serverClient, DarwinTabletProc, TRUE);
-    assert(darwinTabletStylus);
+    if (!darwinTabletStylus)
+        FatalError("Failed to add tablet stylus input device\n");
     darwinTabletStylus->name = strdup("pen");
 
     darwinTabletCursor = AddInputDevice(serverClient, DarwinTabletProc, TRUE);
-    assert(darwinTabletCursor);
+    if (!darwinTabletCursor)
+        FatalError("Failed to add tablet cursor input device\n");
     darwinTabletCursor->name = strdup("cursor");
 
     darwinTabletEraser = AddInputDevice(serverClient, DarwinTabletProc, TRUE);
-    assert(darwinTabletEraser);
+    if (!darwinTabletEraser)
+        FatalError("Failed to add tablet eraser input device\n");
     darwinTabletEraser->name = strdup("eraser");
 
     DarwinEQInit();
@@ -675,8 +679,10 @@ OsVendorInit(void)
     if (serverGeneration == 1) {
         char *lf;
         char *home = getenv("HOME");
-        assert(home);
-        assert(0 < asprintf(&lf, "%s/Library/Logs/X11", home));
+        if (!home)
+            FatalError("HOME is not set\n");
+        if (asprintf(&lf, "%s/Library/Logs/X11", home) < 0)
+            FatalError("Failed to allocate log directory path\n");
 
         /* Ignore errors.  If EEXIST, we don't care.  If anything else,
          * LogInit will handle it for us.
@@ -684,9 +690,9 @@ OsVendorInit(void)
         (void)mkdir(lf, S_IRWXU | S_IRWXG | S_IRWXO);
         free(lf);
 
-        assert(0 <
-               asprintf(&lf, "%s/Library/Logs/X11/%s.log", home,
-                        bundle_id_prefix));
+        if (asprintf(&lf, "%s/Library/Logs/X11/%s.log", home,
+                     bundle_id_prefix) < 0)
+            FatalError("Failed to allocate log file path\n");
         LogInit(lf, ".old");
         free(lf);
 
diff --git a/hw/xquartz/mach-startup/bundle_trampoline.c b/hw/xquartz/mach-startup/bundle_trampoline.c
index 89d4093132..838c06c9ee 100644
--- a/hw/xquartz/mach-startup/bundle_trampoline.c
+++ b/hw/xquartz/mach-startup/bundle_trampoline.c
@@ -26,13 +26,15 @@
  * prior written authorization.
  */
 
-#include <assert.h>
 #include <mach-o/dyld.h>
 #include <libgen.h>
+#include <os/log.h>
 #include <spawn.h>
 #include <sys/syslimits.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
 /* We want XQuartz.app to inherit a login shell environment.  This is handled by the X11.sh
@@ -57,7 +59,10 @@ static char *executable_path() {
     if (_NSGetExecutablePath(buf, &bufsize) == -1) {
         free(buf);
         buf = calloc(1, bufsize);
-        assert(_NSGetExecutablePath(buf, &bufsize) == 0);
+        if (_NSGetExecutablePath(buf, &bufsize) != 0) {
+            os_log_error(OS_LOG_DEFAULT, "Failed to determine executable path");
+            abort();
+        }
     }
 
     return buf;
@@ -72,16 +77,31 @@ int main(int argc, char **argv, char **envp) {
         free(executable);
         asprintf(&executable, "%s/X11", executable_directory);
     }
-    assert(access(executable, X_OK) == 0);
+    if (access(executable, X_OK) != 0) {
+        os_log_error(OS_LOG_DEFAULT, "Cannot execute %{public}s: %{public}s", executable, strerror(errno));
+        abort();
+    }
 
     argv[0] = executable;
 
     posix_spawnattr_t attr;
-    assert(posix_spawnattr_init(&attr) == 0);
-    assert(posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETEXEC) == 0);
+    int error = posix_spawnattr_init(&attr);
+    if (error != 0) {
+        os_log_error(OS_LOG_DEFAULT, "posix_spawnattr_init failed: %{public}s", strerror(error));
+        abort();
+    }
+    error = posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETEXEC);
+    if (error != 0) {
+        os_log_error(OS_LOG_DEFAULT, "posix_spawnattr_setflags failed: %{public}s", strerror(error));
+        abort();
+    }
 
     pid_t child_pid;
-    assert(posix_spawn(&child_pid, executable, NULL, &attr, argv, envp) == 0);
+    error = posix_spawn(&child_pid, executable, NULL, &attr, argv, envp);
+    if (error != 0) {
+        os_log_error(OS_LOG_DEFAULT, "posix_spawn failed for %{public}s: %{public}s", executable, strerror(error));
+        abort();
+    }
 
     return EXIT_FAILURE;
 }