diff --git a/src/futhark.nim b/src/futhark.nim
index c5516cd..64691da 100644
--- a/src/futhark.nim
+++ b/src/futhark.nim
@@ -20,10 +20,23 @@ const
     "shl", "shr", "static",
     "template", "try", "tuple", "type",
     "using",
-    "var", "void",
+    "var",
     "when", "while",
     "xor",
     "yield"]
+  # The following list is generated by running `jq '.entries[] | select (.type == "skType").name'` on the output of `nim jsondoc system.nim`
+  systemTypes = ["int", "int8", "int16", "int32", "int64", "uint", "uint8",
+    "uint16", "uint32", "uint64", "float", "float32", "float64", "char",
+    "string", "cstring", "pointer", "typedesc", "`ptr`", "`ref`", "void",
+    "auto", "any", "untyped", "typed", "bool", "SomeSignedInt",
+    "SomeUnsignedInt", "SomeInteger", "SomeFloat", "SomeNumber", "SomeOrdinal",
+    "`static`", "`type`", "TypeOfMode", "iterable", "Ordinal", "range",
+    "array", "openArray", "varargs", "seq", "set", "UncheckedArray", "sink",
+    "lent", "HSlice", "Slice", "byte", "Natural", "Positive", "RootObj",
+    "RootRef", "RootEffect", "StackTraceEntry", "Exception", "Defect",
+    "CatchableError", "JsRoot", "owned", "Endianness", "TaintedString",
+    "csize", "AllocStats", "GC_Strategy", "PFrame", "TFrame", "ForeignCell",
+    "Channel", "BackwardsIndex", "NimNode", "ForLoopStmt"]
   syspaths {.strdefine.} = ""
   nodeclguards = defined(nodeclguards)
   noopaquetypes = defined(noopaquetypes)
@@ -204,11 +217,11 @@ proc sanitizeName(usedNames: var HashSet[string], origName: string, kind: string
   var
     normalizedName = result.nimIdentNormalize()
     renamed = false
-  if usedNames.contains(normalizedName) or result in builtins:
+  if usedNames.contains(normalizedName) or normalizedName in builtins or normalizedName in systemTypes:
     result.add "_" & kind
     normalizedName.add kind
     renamed = true
-  if usedNames.contains(normalizedName) or result in builtins:
+  if usedNames.contains(normalizedName) or normalizedName in builtins or normalizedName in systemTypes:
     let uniqueTail = hash(origName).uint32.toHex
     result.add "_" & uniqueTail
     normalizedName.add uniqueTail
@@ -294,7 +307,7 @@ proc addEntity(state: var State, name: string, entity: JsonNode) =
   state.opaqueTypes.excl name
 
 proc addOpaque(state: var State, opaque: string) =
-  if not state.entities.hasKey(opaque) and opaque notin builtins:
+  if not state.entities.hasKey(opaque) and opaque notin builtins and opaque notin systemTypes:
     state.opaqueTypes.incl opaque
 
 proc toNimType(json: JsonNode, state: var State): NimNode =