diff --git a/src/apps/cam/sdl_sink.cpp b/src/apps/cam/sdl_sink.cpp
index 30cfdf0af..17a9e04b5 100644
--- a/src/apps/cam/sdl_sink.cpp
+++ b/src/apps/cam/sdl_sink.cpp
@@ -112,7 +112,9 @@ int SDLSink::configure(const libcamera::CameraConfiguration &config)
 #endif
 #if SDL_VERSION_ATLEAST(2, 0, 16)
 	else if (cfg.pixelFormat == libcamera::formats::NV12)
-		texture_ = std::make_unique<SDLTextureNV12>(rect_, cfg.stride);
+		texture_ = std::make_unique<SDLTextureNV>(rect_, SDL_PIXELFORMAT_NV12, cfg.stride);
+	else if (cfg.pixelFormat == libcamera::formats::NV21)
+		texture_ = std::make_unique<SDLTextureNV>(rect_, SDL_PIXELFORMAT_NV21, cfg.stride);
 #endif
 	else {
 		std::cerr << "Unsupported pixel format " << cfg.pixelFormat << std::endl;
diff --git a/src/apps/cam/sdl_texture_yuv.cpp b/src/apps/cam/sdl_texture_yuv.cpp
index bed297d28..40d1a3ae9 100644
--- a/src/apps/cam/sdl_texture_yuv.cpp
+++ b/src/apps/cam/sdl_texture_yuv.cpp
@@ -7,16 +7,21 @@
 
 #include "sdl_texture_yuv.h"
 
-using namespace libcamera;
+#include <assert.h>
 
 #if SDL_VERSION_ATLEAST(2, 0, 16)
-SDLTextureNV12::SDLTextureNV12(const SDL_Rect &rect, unsigned int stride)
-	: SDLTexture(rect, SDL_PIXELFORMAT_NV12, stride)
+SDLTextureNV::SDLTextureNV(const SDL_Rect &rect, uint32_t pixelFormat, unsigned int stride)
+	: SDLTexture(rect, pixelFormat, stride)
 {
+	assert(pixelFormat == SDL_PIXELFORMAT_NV12 || pixelFormat == SDL_PIXELFORMAT_NV21);
 }
 
-void SDLTextureNV12::update(libcamera::Span<const libcamera::Span<const uint8_t>> data)
+void SDLTextureNV::update(libcamera::Span<const libcamera::Span<const uint8_t>> data)
 {
+	assert(data.size() == 2);
+	assert(data[0].size_bytes() == std::size_t(rect_.h) * std::size_t(stride_));
+	assert(data[1].size_bytes() == std::size_t(rect_.h) * std::size_t(stride_) / 2);
+
 	SDL_UpdateNVTexture(ptr_, nullptr, data[0].data(), stride_,
 			    data[1].data(), stride_);
 }
diff --git a/src/apps/cam/sdl_texture_yuv.h b/src/apps/cam/sdl_texture_yuv.h
index c271f901b..8e73506d1 100644
--- a/src/apps/cam/sdl_texture_yuv.h
+++ b/src/apps/cam/sdl_texture_yuv.h
@@ -10,10 +10,10 @@
 #include "sdl_texture.h"
 
 #if SDL_VERSION_ATLEAST(2, 0, 16)
-class SDLTextureNV12 : public SDLTexture
+class SDLTextureNV final : public SDLTexture
 {
 public:
-	SDLTextureNV12(const SDL_Rect &rect, unsigned int stride);
+	SDLTextureNV(const SDL_Rect &rect, uint32_t pixelFormat, unsigned int stride);
 	void update(libcamera::Span<const libcamera::Span<const uint8_t>> data) override;
 };
 #endif