diff --git a/src/compiler/compile/css/Stylesheet.ts b/src/compiler/compile/css/Stylesheet.ts
index ed1682378c4e..685cc0dfe0d2 100644
--- a/src/compiler/compile/css/Stylesheet.ts
+++ b/src/compiler/compile/css/Stylesheet.ts
@@ -1,3 +1,17 @@
+// TODO move pushArray to npm module
+function pushArray(thisArray: any[], ...otherList: any[]) {
+  let count = 0;
+  for (let a = 0; a < otherList.length; a++) {
+    const other = otherList[a];
+    for (let i = 0; i < other.length; i++) {
+      thisArray.push(other[i]);
+    }
+    count += other.length;
+  }
+  return count;
+}
+
+
 import MagicString from 'magic-string';
 import { walk } from 'estree-walker';
 import Selector from './Selector';
@@ -351,7 +365,7 @@ export default class Stylesheet {
 							const at_rule_declarations = node.block.children
 								.filter(node => node.type === 'Declaration')
 								.map(node => new Declaration(node));
-							atrule.declarations.push(...at_rule_declarations);
+							pushArray(atrule.declarations,at_rule_declarations);
 						}
 
 						current_atrule = atrule;
diff --git a/src/compiler/compile/render_dom/wrappers/Element/index.ts b/src/compiler/compile/render_dom/wrappers/Element/index.ts
index 9ec36b12d7da..137f16531bf5 100644
--- a/src/compiler/compile/render_dom/wrappers/Element/index.ts
+++ b/src/compiler/compile/render_dom/wrappers/Element/index.ts
@@ -1,3 +1,17 @@
+// TODO move pushArray to npm module
+function pushArray(thisArray: any[], ...otherList: any[]) {
+  let count = 0;
+  for (let a = 0; a < otherList.length; a++) {
+    const other = otherList[a];
+    for (let i = 0; i < other.length; i++) {
+      thisArray.push(other[i]);
+    }
+    count += other.length;
+  }
+  return count;
+}
+
+
 import Renderer from '../../Renderer';
 import Element from '../../../nodes/Element';
 import Wrapper from '../shared/Wrapper';
@@ -596,7 +610,7 @@ export default class ElementWrapper extends Wrapper {
 		this.attributes.forEach((attribute) => {
 			if (attribute.node.name === 'class') {
 				const dependencies = attribute.node.get_dependencies();
-				this.class_dependencies.push(...dependencies);
+				pushArray(this.class_dependencies,dependencies);
 			}
 		});
 
diff --git a/src/compiler/compile/render_dom/wrappers/IfBlock.ts b/src/compiler/compile/render_dom/wrappers/IfBlock.ts
index 557176bace20..48665c808166 100644
--- a/src/compiler/compile/render_dom/wrappers/IfBlock.ts
+++ b/src/compiler/compile/render_dom/wrappers/IfBlock.ts
@@ -1,3 +1,17 @@
+// TODO move pushArray to npm module
+function pushArray(thisArray: any[], ...otherList: any[]) {
+  let count = 0;
+  for (let a = 0; a < otherList.length; a++) {
+    const other = otherList[a];
+    for (let i = 0; i < other.length; i++) {
+      thisArray.push(other[i]);
+    }
+    count += other.length;
+  }
+  return count;
+}
+
+
 import Wrapper from './shared/Wrapper';
 import Renderer from '../Renderer';
 import Block from '../Block';
@@ -166,7 +180,7 @@ export default class IfBlockWrapper extends Wrapper {
 			block.has_outro_method = has_outros;
 		});
 
-		renderer.blocks.push(...blocks);
+		pushArray(renderer.blocks,blocks);
 	}
 
 	render(
diff --git a/src/compiler/preprocess/index.ts b/src/compiler/preprocess/index.ts
index 10771603d76e..c3791ea3712e 100644
--- a/src/compiler/preprocess/index.ts
+++ b/src/compiler/preprocess/index.ts
@@ -1,3 +1,17 @@
+// TODO move pushArray to npm module
+function pushArray(thisArray: any[], ...otherList: any[]) {
+  let count = 0;
+  for (let a = 0; a < otherList.length; a++) {
+    const other = otherList[a];
+    for (let i = 0; i < other.length; i++) {
+      thisArray.push(other[i]);
+    }
+    count += other.length;
+  }
+  return count;
+}
+
+
 import { RawSourceMap, DecodedSourceMap } from '@ampproject/remapping/dist/types/types';
 import { getLocator } from 'locate-character';
 import { MappedCode, SourceLocation, parse_attached_sourcemap, sourcemap_add_offset, combine_sourcemaps } from '../utils/mapped_code';
@@ -48,7 +62,7 @@ class PreprocessResult implements Source {
 		}
 
 		if (dependencies) {
-			this.dependencies.push(...dependencies);
+			pushArray(this.dependencies,dependencies);
 		}
 	}
 
@@ -165,7 +179,7 @@ async function process_tag(
 		});
 
 		if (!processed) return no_change();
-		if (processed.dependencies) dependencies.push(...processed.dependencies);
+		if (processed.dependencies) pushArray(dependencies,processed.dependencies);
 		if (!processed.map && processed.code === content) return no_change();
 
 		return processed_tag_to_code(processed, tag_name, attributes, slice_source(content, tag_offset, source));