diff --git a/spec/compiler/semantic/static_array_spec.cr b/spec/compiler/semantic/static_array_spec.cr
index cd2db6e88159..0112584753c7 100644
--- a/spec/compiler/semantic/static_array_spec.cr
+++ b/spec/compiler/semantic/static_array_spec.cr
@@ -155,4 +155,28 @@ describe "Semantic: static array" do
       ),
       "expected argument #1 to 'fn' to be StaticArray(Int32, 11), not StaticArray(Int32, 10)"
   end
+
+  it "doesn't crash on sizeof (#8858)" do
+    assert_error %(
+      alias BadArray = Int32[sizeof(Int32)]
+    ),
+      "can't use sizeof(Int32) as a generic type argument"
+  end
+
+  it "doesn't crash on instance_sizeof (#8858)" do
+    assert_error %(
+      alias BadArray = Int32[instance_sizeof(String)]
+    ),
+      "can't use instance_sizeof(String) as a generic type argument"
+  end
+
+  it "doesn't crash on offsetof (#8858)" do
+    assert_error %(
+      class Foo
+        @foo : Int32 = 0
+      end
+      alias BadArray = Int32[offsetof(Foo, @foo)]
+    ),
+      "can't use offsetof(Foo, @foo) as a generic type argument"
+  end
 end
diff --git a/src/compiler/crystal/semantic/type_lookup.cr b/src/compiler/crystal/semantic/type_lookup.cr
index 7a98450cc72b..64c3b319cf6e 100644
--- a/src/compiler/crystal/semantic/type_lookup.cr
+++ b/src/compiler/crystal/semantic/type_lookup.cr
@@ -247,6 +247,10 @@ class Crystal::Type
             type_var.raise "can only splat tuple type, not #{splat_type}"
           end
           next
+        when SizeOf, InstanceSizeOf, OffsetOf
+          next unless @raise
+
+          type_var.raise "can't use #{type_var} as a generic type argument"
         end
 
         # Check the case of T resolving to a number
diff --git a/src/compiler/crystal/syntax/parser.cr b/src/compiler/crystal/syntax/parser.cr
index adcbcabeece5..e554f500b738 100644
--- a/src/compiler/crystal/syntax/parser.cr
+++ b/src/compiler/crystal/syntax/parser.cr
@@ -5771,6 +5771,7 @@ module Crystal
     end
 
     def parse_sizeof(klass)
+      sizeof_location = @token.location
       next_token_skip_space
 
       check :OP_LPAREN
@@ -5785,10 +5786,11 @@ module Crystal
       check :OP_RPAREN
       next_token_skip_space
 
-      klass.new(exp).at_end(end_location)
+      klass.new(exp).at(sizeof_location).at_end(end_location)
     end
 
     def parse_offsetof
+      offsetof_location = @token.location
       next_token_skip_space
       check :OP_LPAREN
 
@@ -5817,7 +5819,7 @@ module Crystal
       check :OP_RPAREN
       next_token_skip_space
 
-      OffsetOf.new(type, offset).at_end(end_location)
+      OffsetOf.new(type, offset).at(offsetof_location).at_end(end_location)
     end
 
     def parse_type_def