diff --git a/activities/views/compose.py b/activities/views/compose.py
index 827b105..8d8ef96 100644
--- a/activities/views/compose.py
+++ b/activities/views/compose.py
@@ -204,7 +204,30 @@ class ImageUpload(FormView):
     template_name = "activities/_image_upload.html"
 
     class form_class(forms.Form):
-        image = forms.ImageField()
+        image = forms.ImageField(
+            widget=forms.FileInput(
+                attrs={
+                    "_": f"""
+                        on change
+                            if me.files[0].size > {settings.SETUP.MEDIA_MAX_IMAGE_FILESIZE_MB * 1024 ** 2}
+                                add [@disabled=] to #upload
+
+                                remove <ul.errorlist/>
+                                make <ul.errorlist/> called errorlist
+                                make <li/> called error
+                                set size_in_mb to (me.files[0].size / 1024 / 1024).toFixed(2)
+                                put 'File must be 10MB or less (actual: ' + size_in_mb + 'MB)' into error
+                                put error into errorlist
+                                put errorlist before me
+                            else
+                                remove @disabled from #upload
+                                remove <ul.errorlist/>
+                            end
+                        end
+                    """
+                }
+            )
+        )
         description = forms.CharField(required=False)
 
         def clean_image(self):
@@ -214,7 +237,9 @@ class ImageUpload(FormView):
             if value.size > max_bytes:
                 # Erase the file from our data to stop trying to show it again
                 self.files = {}
-                raise forms.ValidationError(f"File must be {max_mb}MB or less")
+                raise forms.ValidationError(
+                    f"File must be {max_mb}MB or less (actual: {value.size / 1024 ** 2:.2f})"
+                )
             return value
 
     def form_invalid(self, form):
diff --git a/static/css/style.css b/static/css/style.css
index 2888880..312a837 100644
--- a/static/css/style.css
+++ b/static/css/style.css
@@ -1034,6 +1034,7 @@ button.toggle,
 button[disabled],
 .button[disabled] {
     background: var(--color-button-disabled);
+    cursor: not-allowed;
 }
 
 button.left,
diff --git a/templates/activities/_image_upload.html b/templates/activities/_image_upload.html
index c812c44..dec9160 100644
--- a/templates/activities/_image_upload.html
+++ b/templates/activities/_image_upload.html
@@ -9,7 +9,7 @@
     {% include "forms/_field.html" with field=form.image %}
     {% include "forms/_field.html" with field=form.description %}
     <div class="buttons">
-        <button _="on click show #attachmentProgress with display:block then hide me">Upload</button>
+        <button id="upload" _="on click show #attachmentProgress with display:block then hide me">Upload</button>
         <progress id="attachmentProgress" value="0" max="100"></progress>
     </div>
 </form>