diff --git a/ext/native/thin3d/DataFormatGL.cpp b/ext/native/thin3d/DataFormatGL.cpp
index e2aa7a7a1b6e..5d48f15868fd 100644
--- a/ext/native/thin3d/DataFormatGL.cpp
+++ b/ext/native/thin3d/DataFormatGL.cpp
@@ -81,7 +81,6 @@ bool Thin3DFormatToFormatAndType(DataFormat fmt, GLuint &internalFormat, GLuint
 #endif
 
 	default:
-		_assert_msg_(G3D, false, "Thin3d GL: Unsupported texture format %d", (int)fmt);
 		return false;
 	}
 	return true;
diff --git a/ext/native/thin3d/GLQueueRunner.cpp b/ext/native/thin3d/GLQueueRunner.cpp
index a895ed4649e8..3ea363696857 100644
--- a/ext/native/thin3d/GLQueueRunner.cpp
+++ b/ext/native/thin3d/GLQueueRunner.cpp
@@ -984,7 +984,8 @@ void GLQueueRunner::PerformReadback(const GLRStep &pass) {
 	GLuint type;
 	int alignment;
 	if (!Draw::Thin3DFormatToFormatAndType(pass.readback.dstFormat, internalFormat, format, type, alignment)) {
-		assert(false);
+		ELOG("Readback failed - format %d not available", (int)pass.readback.dstFormat);
+		return;
 	}
 	int pixelStride = pass.readback.srcRect.w;
 	// Apply the correct alignment.