diff --git a/core/image.cpp b/core/image.cpp
index f43c26ab194..b904d05c2bc 100644
--- a/core/image.cpp
+++ b/core/image.cpp
@@ -1448,6 +1448,8 @@ Error Image::generate_mipmaps(bool p_renormalize) {
 
 	ERR_FAIL_COND_V_MSG(!_can_modify(format), ERR_UNAVAILABLE, "Cannot generate mipmaps in compressed or custom image formats.");
 
+	ERR_FAIL_COND_V_MSG(format == FORMAT_RGBA4444 || format == FORMAT_RGBA5551, ERR_UNAVAILABLE, "Cannot generate mipmaps in custom image formats.");
+
 	ERR_FAIL_COND_V_MSG(width == 0 || height == 0, ERR_UNCONFIGURED, "Cannot generate mipmaps with width or height equal to 0.");
 
 	int mmcount;
diff --git a/modules/etc/image_etc.cpp b/modules/etc/image_etc.cpp
index b80138c99d8..7be27d606c1 100644
--- a/modules/etc/image_etc.cpp
+++ b/modules/etc/image_etc.cpp
@@ -143,9 +143,15 @@ static void _compress_etc(Image *p_img, float p_lossy_quality, bool force_etc1_f
 		// If VRAM compression is using ETC, but image has alpha, convert to RGBA4444 or LA8
 		// This saves space while maintaining the alpha channel
 		if (detected_channels == Image::DETECTED_RGBA) {
+
+			if (p_img->has_mipmaps()) {
+				// Image doesn't support mipmaps with RGBA4444 textures
+				p_img->clear_mipmaps();
+			}
 			p_img->convert(Image::FORMAT_RGBA4444);
 			return;
 		} else if (detected_channels == Image::DETECTED_LA) {
+
 			p_img->convert(Image::FORMAT_LA8);
 			return;
 		}