diff --git a/lib/std/assertions.nim b/lib/std/assertions.nim
index 229033c585..a249d77516 100644
--- a/lib/std/assertions.nim
+++ b/lib/std/assertions.nim
@@ -7,6 +7,10 @@
 #    distribution, for details about the copyright.
 #
 
+when not defined(nimPreviewSlimSystem) and not declared(sysFatal):
+  include "system/rawquits"
+  include "system/fatal"
+
 ## This module implements assertion handling.
 
 import std/private/miscdollars
@@ -26,7 +30,10 @@ proc `$`(info: InstantiationInfo): string =
 
 proc raiseAssert*(msg: string) {.noinline, noreturn, nosinks.} =
   ## Raises an `AssertionDefect` with `msg`.
-  raise newException(AssertionDefect, msg)
+  when defined(nimPreviewSlimSystem):
+    raise newException(AssertionDefect, msg)
+  else:
+    sysFatal(AssertionDefect, msg)
 
 proc failedAssertImpl*(msg: string) {.raises: [], tags: [].} =
   ## Raises an `AssertionDefect` with `msg`, but this is hidden
diff --git a/lib/system.nim b/lib/system.nim
index e9c9ebfebc..d8fafc0ef2 100644
--- a/lib/system.nim
+++ b/lib/system.nim
@@ -1081,31 +1081,9 @@ proc align(address, alignment: int): int =
   else:
     result = (address + (alignment - 1)) and not (alignment - 1)
 
-when defined(nimNoQuit):
-  proc rawQuit(errorcode: int = QuitSuccess) = discard "ignoring quit"
-
-elif defined(genode):
-  import genode/env
-
-  var systemEnv {.exportc: runtimeEnvSym.}: GenodeEnvPtr
-
-  type GenodeEnv* = GenodeEnvPtr
-    ## Opaque type representing Genode environment.
-
-  proc rawQuit(env: GenodeEnv; errorcode: int) {.magic: "Exit", noreturn,
-    importcpp: "#->parent().exit(@); Genode::sleep_forever()", header: "<base/sleep.h>".}
-
-  proc rawQuit(errorcode: int = QuitSuccess) {.inline, noreturn.} =
-    systemEnv.rawQuit(errorcode)
-
-
-elif defined(js) and defined(nodejs) and not defined(nimscript):
-  proc rawQuit(errorcode: int = QuitSuccess) {.magic: "Exit",
-    importc: "process.exit", noreturn.}
-
-else:
-  proc rawQuit(errorcode: cint) {.
-    magic: "Exit", importc: "exit", header: "<stdlib.h>", noreturn.}
+include system/rawquits
+when defined(genode):
+  export GenodeEnv
 
 template sysAssert(cond: bool, msg: string) =
   when defined(useSysAssert):
diff --git a/lib/system/rawquits.nim b/lib/system/rawquits.nim
new file mode 100644
index 0000000000..f0ead10c6c
--- /dev/null
+++ b/lib/system/rawquits.nim
@@ -0,0 +1,27 @@
+import system/ctypes
+
+when defined(nimNoQuit):
+  proc rawQuit(errorcode: int = QuitSuccess) = discard "ignoring quit"
+
+elif defined(genode):
+  import genode/env
+
+  var systemEnv {.exportc: runtimeEnvSym.}: GenodeEnvPtr
+
+  type GenodeEnv = GenodeEnvPtr
+    ## Opaque type representing Genode environment.
+
+  proc rawQuit(env: GenodeEnv; errorcode: int) {.magic: "Exit", noreturn,
+    importcpp: "#->parent().exit(@); Genode::sleep_forever()", header: "<base/sleep.h>".}
+
+  proc rawQuit(errorcode: int = QuitSuccess) {.inline, noreturn.} =
+    systemEnv.rawQuit(errorcode)
+
+
+elif defined(js) and defined(nodejs) and not defined(nimscript):
+  proc rawQuit(errorcode: int = QuitSuccess) {.magic: "Exit",
+    importc: "process.exit", noreturn.}
+
+else:
+  proc rawQuit(errorcode: cint) {.
+    magic: "Exit", importc: "exit", header: "<stdlib.h>", noreturn.}
\ No newline at end of file
diff --git a/tests/assert/panicoverride.nim b/tests/assert/panicoverride.nim
new file mode 100644
index 0000000000..53ad64215b
--- /dev/null
+++ b/tests/assert/panicoverride.nim
@@ -0,0 +1,15 @@
+# panicoverride.nim
+
+proc printf(fmt: cstring) {.varargs, importc, header:"stdio.h".}
+proc exit(code: cint) {.importc, header:"stdlib.h".}
+
+{.push stack_trace: off, profiler:off.}
+
+proc rawoutput(s: cstring) =
+  printf("RAW: %s\n", s)
+  
+proc panic(s: cstring) {.noreturn.} =
+  printf("PANIC: %s\n", s)
+  exit(0)
+
+{.pop.}
\ No newline at end of file
diff --git a/tests/assert/t21195.nim b/tests/assert/t21195.nim
new file mode 100644
index 0000000000..b690d22a0f
--- /dev/null
+++ b/tests/assert/t21195.nim
@@ -0,0 +1,6 @@
+discard """
+  matrix: "--verbosity:0 --os:standalone --mm:none"
+"""
+# bug #21195
+var n = 11
+assert(n == 12)
diff --git a/tests/assert/tassert_c.nim b/tests/assert/tassert_c.nim
index 110a9aabf6..4d49a60350 100644
--- a/tests/assert/tassert_c.nim
+++ b/tests/assert/tassert_c.nim
@@ -1,8 +1,8 @@
 discard """
-  cmd: "nim $target $options --excessiveStackTrace:off $file"
+  cmd: "nim $target $options -d:nimPreviewSlimSystem --excessiveStackTrace:off $file"
   output: '''true'''
 """
-
+import std/assertions
 const expected = """
 tassert_c.nim(35)        tassert_c
 tassert_c.nim(34)        foo
diff --git a/tests/errmsgs/t9768.nim b/tests/errmsgs/t9768.nim
index 058d297b35..b5ff583673 100644
--- a/tests/errmsgs/t9768.nim
+++ b/tests/errmsgs/t9768.nim
@@ -1,14 +1,14 @@
 discard """
   errormsg: "unhandled exception: t9768.nim(24, 3) `a < 4`  [AssertionDefect]"
   file: "std/assertions.nim"
+  matrix: "-d:nimPreviewSlimSystem"
   nimout: '''
 stack trace: (most recent call last)
 t9768.nim(29, 33)        main
 t9768.nim(24, 11)        foo1
 '''
 """
-
-
+import std/assertions