diff --git a/src/video_provider_vs.cpp b/src/video_provider_vs.cpp
index 8ecd621bb..bde0f9a70 100644
--- a/src/video_provider_vs.cpp
+++ b/src/video_provider_vs.cpp
@@ -141,7 +141,13 @@ VapoursynthVideoProvider::VapoursynthVideoProvider(agi::fs::path const& filename
 	// Assume constant frame rate, since handling VFR would require going through all frames when loading.
 	// Users can load custom timecodes files to deal with VFR.
 	// Alternatively (TODO) the provider could read timecodes and keyframes from a second output node.
-	fps = agi::vfr::Framerate(vi->fpsNum, vi->fpsDen);
+	int fpsNum = vi->fpsNum;
+	int fpsDen = vi->fpsDen;
+	if (fpsDen == 0) {
+		fpsNum = 25;
+		fpsDen = 1;
+	}
+	fps = agi::vfr::Framerate(fpsNum, fpsDen);
 
 	// Find the first frame to get some info
 	const VSFrame *frame;