diff --git a/src/webgl/material.js b/src/webgl/material.js
index 594ddecfb3..d7a375d93d 100644
--- a/src/webgl/material.js
+++ b/src/webgl/material.js
@@ -523,18 +523,15 @@ function material(p5, fn) {
       const fragString = await fragSrc.join('\n');
 
       // Test if we've loaded GLSL or not by checking for the existence of `void main`
-      let loadedShader;
-      if (/void\s+main/.exec(fragString)) {
-        loadedShader = this._internal(() =>
-          this.createFilterShader(fragString, true)
-        );
-      } else {
-        loadedShader = this._internal(() =>
-          withGlobalStrands(this, () =>
-            this.baseFilterShader().modify(new Function(fragString))
-          )
-        );
-      }
+      const build = /void\s+main/.exec(fragString)
+        ? () => this.createFilterShader(fragString, true)
+        : () =>
+            withGlobalStrands(this, () =>
+              this.baseFilterShader().modify(new Function(fragString))
+            );
+
+      // _internal() is provided by FES, which is not included in p5.min.js
+      let loadedShader = this._internal ? this._internal(build) : build();
 
       if (successCallback) {
         loadedShader = successCallback(loadedShader) || loadedShader;
@@ -1637,9 +1634,9 @@ function material(p5, fn) {
   fn.loadMaterialShader = async function (url, onSuccess, onFail) {
     try {
       const cb = await urlToStrandsCallback(url);
-      let shader = this._internal(() =>
-        withGlobalStrands(this, () => this.buildMaterialShader(cb))
-      );
+      const build = () =>
+        withGlobalStrands(this, () => this.buildMaterialShader(cb));
+      let shader = this._internal ? this._internal(build) : build();
       if (onSuccess) {
         shader = onSuccess(shader) || shader;
       }
@@ -1857,9 +1854,9 @@ function material(p5, fn) {
   fn.loadNormalShader = async function (url, onSuccess, onFail) {
     try {
       const cb = await urlToStrandsCallback(url);
-      let shader = this._internal(() =>
-        this.withGlobalStrands(this, () => this.buildNormalShader(cb))
-      );
+      const build = () =>
+        withGlobalStrands(this, () => this.buildNormalShader(cb));
+      let shader = this._internal ? this._internal(build) : build();
       if (onSuccess) {
         shader = onSuccess(shader) || shader;
       }
@@ -2022,9 +2019,9 @@ function material(p5, fn) {
   fn.loadColorShader = async function (url, onSuccess, onFail) {
     try {
       const cb = await urlToStrandsCallback(url);
-      let shader = this._internal(() =>
-        withGlobalStrands(this, () => this.buildColorShader(cb))
-      );
+      const build = () =>
+        withGlobalStrands(this, () => this.buildColorShader(cb));
+      let shader = this._internal ? this._internal(build) : build();
       if (onSuccess) {
         shader = onSuccess(shader) || shader;
       }
@@ -2285,9 +2282,9 @@ function material(p5, fn) {
   fn.loadStrokeShader = async function (url, onSuccess, onFail) {
     try {
       const cb = await urlToStrandsCallback(url);
-      let shader = this._internal(() =>
-        withGlobalStrands(this, () => this.buildStrokeShader(cb))
-      );
+      const build = () =>
+        withGlobalStrands(this, () => this.buildStrokeShader(cb));
+      let shader = this._internal ? this._internal(build) : build();
       if (onSuccess) {
         shader = onSuccess(shader) || shader;
       }
diff --git a/test/unit/assets/testColor.js b/test/unit/assets/testColor.js
new file mode 100644
index 0000000000..1dcfe5f181
--- /dev/null
+++ b/test/unit/assets/testColor.js
@@ -0,0 +1,4 @@
+// Test color shader that swaps the red and green channels
+getFinalColor(color => {
+  return [color.g, color.r, color.b, color.a];
+});
diff --git a/test/unit/assets/testNormal.js b/test/unit/assets/testNormal.js
new file mode 100644
index 0000000000..02fc7290a8
--- /dev/null
+++ b/test/unit/assets/testNormal.js
@@ -0,0 +1,5 @@
+// Test normal shader that shifts every vertex to the right
+getWorldInputs(inputs => {
+  inputs.position.x += 10;
+  return inputs;
+});
diff --git a/test/unit/assets/testStroke.js b/test/unit/assets/testStroke.js
new file mode 100644
index 0000000000..ec706b7700
--- /dev/null
+++ b/test/unit/assets/testStroke.js
@@ -0,0 +1,5 @@
+// Test stroke shader that makes strokes three times as thick
+getWorldInputs(inputs => {
+  inputs.weight *= 3;
+  return inputs;
+});
diff --git a/test/unit/io/loadStrandsShaders.js b/test/unit/io/loadStrandsShaders.js
new file mode 100644
index 0000000000..dd5bc301c6
--- /dev/null
+++ b/test/unit/io/loadStrandsShaders.js
@@ -0,0 +1,81 @@
+import { mockP5, mockP5Prototype, httpMock } from '../../js/mocks';
+import { vi } from 'vitest';
+import files from '../../../src/io/files';
+import material from '../../../src/webgl/material';
+
+// The mock p5 does not include the Friendly Error System, so these tests also
+// cover the minified build, where `_internal()` is not defined.
+suite('load*Shader for p5.strands files', function () {
+  const builtShader = { isBuiltShader: true };
+  const stubbed = [
+    'buildMaterialShader',
+    'buildNormalShader',
+    'buildColorShader',
+    'buildStrokeShader',
+    'baseFilterShader',
+    'createFilterShader'
+  ];
+  const originals = {};
+
+  beforeAll(async () => {
+    files(mockP5, mockP5Prototype);
+    material(mockP5, mockP5Prototype);
+    await httpMock.start({ quiet: true });
+
+    // Stub the shader builders so that only the loading logic is tested
+    for (const name of stubbed) {
+      originals[name] = mockP5Prototype[name];
+    }
+    mockP5Prototype.buildMaterialShader = vi.fn(() => builtShader);
+    mockP5Prototype.buildNormalShader = vi.fn(() => builtShader);
+    mockP5Prototype.buildColorShader = vi.fn(() => builtShader);
+    mockP5Prototype.buildStrokeShader = vi.fn(() => builtShader);
+    mockP5Prototype.baseFilterShader = vi.fn(() => ({
+      modify: vi.fn(() => builtShader)
+    }));
+    mockP5Prototype.createFilterShader = vi.fn(() => builtShader);
+  });
+
+  afterAll(() => {
+    for (const name of stubbed) {
+      mockP5Prototype[name] = originals[name];
+    }
+  });
+
+  const loaders = [
+    ['loadMaterialShader', 'buildMaterialShader', 'testMaterial.js'],
+    ['loadNormalShader', 'buildNormalShader', 'testNormal.js'],
+    ['loadColorShader', 'buildColorShader', 'testColor.js'],
+    ['loadStrokeShader', 'buildStrokeShader', 'testStroke.js']
+  ];
+
+  for (const [loader, builder, file] of loaders) {
+    test(`${loader}() returns the shader built from the file`, async () => {
+      const onFail = vi.fn();
+      const shader = await mockP5Prototype[loader](
+        `/test/unit/assets/${file}`,
+        undefined,
+        onFail
+      );
+      expect(onFail).not.toHaveBeenCalled();
+      expect(mockP5Prototype[builder]).toHaveBeenCalledOnce();
+      assert.strictEqual(shader, builtShader);
+    });
+  }
+
+  test('loadFilterShader() returns the shader built from a p5.strands file', async () => {
+    const shader = await mockP5Prototype.loadFilterShader(
+      '/test/unit/assets/testFilter.js'
+    );
+    expect(mockP5Prototype.baseFilterShader).toHaveBeenCalledOnce();
+    assert.strictEqual(shader, builtShader);
+  });
+
+  test('loadFilterShader() returns the shader built from a GLSL file', async () => {
+    const shader = await mockP5Prototype.loadFilterShader(
+      '/test/unit/assets/frag.glsl'
+    );
+    expect(mockP5Prototype.createFilterShader).toHaveBeenCalledOnce();
+    assert.strictEqual(shader, builtShader);
+  });
+});
diff --git a/test/unit/visual/cases/webgl.js b/test/unit/visual/cases/webgl.js
index 757e597e47..90c5d636fb 100644
--- a/test/unit/visual/cases/webgl.js
+++ b/test/unit/visual/cases/webgl.js
@@ -743,6 +743,48 @@ visualSuite('WebGL', function () {
       p5.filter(filterShader);
       screenshot();
     });
+
+    visualTest('loadNormalShader', async (p5, screenshot) => {
+      p5.createCanvas(50, 50, p5.WEBGL);
+      const normalShader = await p5.loadNormalShader(
+        '/test/unit/assets/testNormal.js'
+      );
+
+      // The shader should shift the plane to the right
+      p5.noStroke();
+      p5.shader(normalShader);
+      p5.plane(20, 20);
+      screenshot();
+    });
+
+    visualTest('loadColorShader', async (p5, screenshot) => {
+      p5.createCanvas(50, 50, p5.WEBGL);
+      const colorShader = await p5.loadColorShader(
+        '/test/unit/assets/testColor.js'
+      );
+
+      // The shader should swap red and green, so the plane appears green
+      p5.noStroke();
+      p5.fill(255, 0, 0);
+      p5.shader(colorShader);
+      p5.plane(20, 20);
+      screenshot();
+    });
+
+    visualTest('loadStrokeShader', async (p5, screenshot) => {
+      p5.createCanvas(50, 50, p5.WEBGL);
+      const strokeShader = await p5.loadStrokeShader(
+        '/test/unit/assets/testStroke.js'
+      );
+
+      // The shader should make the line three times as thick
+      p5.background(255);
+      p5.stroke(0);
+      p5.strokeWeight(4);
+      p5.strokeShader(strokeShader);
+      p5.line(-20, 0, 20, 0);
+      screenshot();
+    });
   });
 
   visualSuite('Strokes', function () {
diff --git a/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadColorShader/000.png b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadColorShader/000.png
new file mode 100644
index 0000000000..873908eaa7
Binary files /dev/null and b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadColorShader/000.png differ
diff --git a/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadColorShader/metadata.json b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadColorShader/metadata.json
new file mode 100644
index 0000000000..2d4bfe30da
--- /dev/null
+++ b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadColorShader/metadata.json
@@ -0,0 +1,3 @@
+{
+  "numScreenshots": 1
+}
\ No newline at end of file
diff --git a/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadNormalShader/000.png b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadNormalShader/000.png
new file mode 100644
index 0000000000..cbf048726d
Binary files /dev/null and b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadNormalShader/000.png differ
diff --git a/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadNormalShader/metadata.json b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadNormalShader/metadata.json
new file mode 100644
index 0000000000..2d4bfe30da
--- /dev/null
+++ b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadNormalShader/metadata.json
@@ -0,0 +1,3 @@
+{
+  "numScreenshots": 1
+}
\ No newline at end of file
diff --git a/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadStrokeShader/000.png b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadStrokeShader/000.png
new file mode 100644
index 0000000000..62778803d0
Binary files /dev/null and b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadStrokeShader/000.png differ
diff --git a/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadStrokeShader/metadata.json b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadStrokeShader/metadata.json
new file mode 100644
index 0000000000..2d4bfe30da
--- /dev/null
+++ b/test/unit/visual/screenshots/WebGL/ShaderFunctionality/loadStrokeShader/metadata.json
@@ -0,0 +1,3 @@
+{
+  "numScreenshots": 1
+}
\ No newline at end of file