diff --git a/doc/errors/index.md b/doc/errors/index.md
index 21a033cd23..37f59aa553 100644
--- a/doc/errors/index.md
+++ b/doc/errors/index.md
@@ -235,7 +235,7 @@ A `WebGLArrayBuffer` must either be of type `ELEMENT_ARRAY_BUFFER` or `ARRAY_BUF
 
 ### 63
 
-Support for the `OES_element_index_uint` WebGL extension is mandatory for WebGL layers.
+Support for the `OES_element_index_uint`, `OES_texture_float`, and `OES_texture_float_linear` WebGL extensions are mandatory for WebGL layers.
 
 ### 64
 
diff --git a/src/ol/webgl/Helper.js b/src/ol/webgl/Helper.js
index 25e21de657..fc580eb086 100644
--- a/src/ol/webgl/Helper.js
+++ b/src/ol/webgl/Helper.js
@@ -279,7 +279,12 @@ class WebGLHelper extends Disposable {
     this.currentProgram_ = null;
 
     assert(includes(getSupportedExtensions(), 'OES_element_index_uint'), 63);
+    assert(includes(getSupportedExtensions(), 'OES_texture_float'), 63);
+    assert(includes(getSupportedExtensions(), 'OES_texture_float_linear'), 63);
+
     gl.getExtension('OES_element_index_uint');
+    gl.getExtension('OES_texture_float');
+    gl.getExtension("OES_texture_float_linear");
 
     this.canvas_.addEventListener(
       ContextEventType.LOST,