diff --git a/test/float_tex.c b/test/float_tex.c
index d493afc5f4fd0..5afd38f5a722b 100644
--- a/test/float_tex.c
+++ b/test/float_tex.c
@@ -6,6 +6,9 @@
 #include <assert.h>
 #include <math.h>
 #include <stdio.h>
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#endif
 
 #define GL_GLEXT_PROTOTYPES
 #define EGL_EGLEXT_PROTOTYPES
@@ -99,6 +102,9 @@ static void glut_draw_callback(void) {
     glVertexAttribPointer(0, 1, GL_FLOAT, GL_FALSE, 0, NULL);
     glDrawArrays(GL_POINTS, 0, NUM_NODES);
     glutSwapBuffers();
+#ifdef __EMSCRIPTEN__
+    EM_ASM(doReftest()); // All done, perform the JS side image comparison reftest.
+#endif
 }
 
 GLuint createShader(const char source[], int type) {
@@ -160,6 +166,11 @@ int main(int argc, char *argv[]) {
     /* Set up glut callback functions */
     glutDisplayFunc(glut_draw_callback);
     gl_init();
+#ifdef __EMSCRIPTEN__
+    // This test kicks off an asynchronous glutMainLoop(), so do not perform a synchronous
+    // reftest immediately after falling out from main.
+    EM_ASM({ delete Module['postRun']; });
+#endif
     glutMainLoop();
     return 0;
 }
diff --git a/test/gl_subdata.c b/test/gl_subdata.c
index 184891e7ec531..ba8d7c5039203 100644
--- a/test/gl_subdata.c
+++ b/test/gl_subdata.c
@@ -7,6 +7,10 @@
 #include <stdio.h>
 #include <string.h>
 
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#endif
+
 #define GL_GLEXT_PROTOTYPES
 #define EGL_EGLEXT_PROTOTYPES
 #include <GL/gl.h>
@@ -99,6 +103,9 @@ static void glut_draw_callback(void) {
     glVertexAttribPointer(0, 1, GL_FLOAT, GL_FALSE, 0, NULL);
     glDrawArrays(GL_POINTS, 0, NUM_NODES);
     glutSwapBuffers();
+#ifdef __EMSCRIPTEN__
+    EM_ASM(doReftest()); // All done, perform the JS side image comparison reftest.
+#endif
 }
 
 GLuint createShader(const char* source, int type) {
@@ -155,6 +162,11 @@ int main(int argc, char *argv[]) {
     /* Set up glut callback functions */
     glutDisplayFunc(glut_draw_callback);
     gl_init();
+#ifdef __EMSCRIPTEN__
+    // This test kicks off an asynchronous glutMainLoop(), so do not perform a synchronous
+    // reftest immediately after falling out from main.
+    EM_ASM({ delete Module['postRun']; });
+#endif
     glutMainLoop();
     return 0;
 }
diff --git a/test/hello_world_gles.c b/test/hello_world_gles.c
index 673a5c90ba5ca..bfb31a1789131 100644
--- a/test/hello_world_gles.c
+++ b/test/hello_world_gles.c
@@ -549,6 +549,9 @@ gears_draw(void)
    draw_gear(gear3, transform, -3.1, 4.2, -2 * angle - 25.0, blue);
 
    glutSwapBuffers();
+#ifdef __EMSCRIPTEN__
+   EM_ASM({if (typeof doReftest !== 'undefined') doReftest();}); // All done, perform the JS side image comparison reftest.
+#endif
 
 #ifdef LONGTEST
    glutPostRedisplay(); // check for issues with not throttling calls
@@ -773,6 +776,11 @@ main(int argc, char *argv[])
    /* Initialize the gears */
    gears_init();
 
+#ifdef __EMSCRIPTEN__
+   // This test kicks off an asynchronous glutMainLoop(), so do not perform a synchronous
+   // reftest immediately after falling out from main.
+   EM_ASM({ if (typeof doReftest !== 'undefined' && Module['postRun'] == doReftest) delete Module['postRun']; });
+#endif
    glutMainLoop();
 
    return 0;
diff --git a/test/hello_world_gles_deriv.c b/test/hello_world_gles_deriv.c
index 592078ed77b99..bfc523067ff74 100644
--- a/test/hello_world_gles_deriv.c
+++ b/test/hello_world_gles_deriv.c
@@ -46,6 +46,9 @@
 #include <string.h>
 #include <sys/time.h>
 #include <unistd.h>
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#endif
 #ifdef __APPLE__
 #include <OpenGL/gl.h>
 #include <Glut/glut.h>
@@ -541,6 +544,9 @@ gears_draw(void)
    draw_gear(gear3, transform, -3.1, 4.2, -2 * angle - 25.0, blue);
 
    glutSwapBuffers();
+#ifdef __EMSCRIPTEN__
+   EM_ASM(doReftest()); // All done, perform the JS side image comparison reftest.
+#endif
 }
 
 /** 
@@ -730,6 +736,11 @@ main(int argc, char *argv[])
    /* Initialize the gears */
    gears_init();
 
+#ifdef __EMSCRIPTEN__
+   // This test kicks off an asynchronous glutMainLoop(), so do not perform a synchronous
+   // reftest immediately after falling out from main.
+   EM_ASM({ if (typeof doReftest !== 'undefined' && Module['postRun'] == doReftest) delete Module['postRun']; });
+#endif
    glutMainLoop();
 
    return 0;
diff --git a/test/hello_world_gles_proxy.c b/test/hello_world_gles_proxy.c
index 0ec0b33744226..ced87ede56ec4 100644
--- a/test/hello_world_gles_proxy.c
+++ b/test/hello_world_gles_proxy.c
@@ -47,6 +47,9 @@
 #include <string.h>
 #include <sys/time.h>
 #include <unistd.h>
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#endif
 #ifdef __APPLE__
 #include <OpenGL/gl.h>
 #include <Glut/glut.h>
@@ -559,12 +562,17 @@ gears_draw(void)
    draw_gear(gear3, transform, -3.1, 4.2, -2 * angle - 25.0, blue);
 
    glutSwapBuffers();
+#ifdef __EMSCRIPTEN__
+   EM_ASM({if (typeof doReftest !== 'undefined') doReftest();}); // All done, perform the JS side image comparison reftest.
+#endif
 
 #ifdef LONGTEST
    glutPostRedisplay(); // check for issues with not throttling calls
 #endif
 
+#ifdef __EMSCRIPTEN__
   EM_ASM({ window.close() });
+#endif
 }
 
 /**
@@ -758,7 +766,7 @@ main(int argc, char *argv[])
    // Don't trigger the reftest immediately after main finishes,
    // this test uses rAF to perform rendering, so let it trigger
    // the reftest after having rendered some frames.
-   EM_ASM(Module['postRun'] = undefined);
+   EM_ASM({ if (typeof doReftest !== 'undefined' && Module['postRun'] == doReftest) delete Module['postRun']; });
 #endif
 
    /* Initialize the window */