diff --git a/remotion-composer/src/CinematicRenderer.tsx b/remotion-composer/src/CinematicRenderer.tsx
index b7c81e25..f3c27412 100644
--- a/remotion-composer/src/CinematicRenderer.tsx
+++ b/remotion-composer/src/CinematicRenderer.tsx
@@ -19,7 +19,15 @@ function resolveAsset(src: string): string {
   }
   const clean = src.replace(/^file:\/\/\/?/, "");
   if (clean.startsWith("/") || /^[A-Za-z]:[/\\]/.test(clean)) {
-    return `file:///${clean.replace(/\\/g, "/")}`;
+    const posix = clean.replace(/\\/g, "/");
+    // POSIX absolute paths already have a leading "/" — file:// + posix
+    // gives exactly three slashes. Windows drive paths (C:/...) need the
+    // extra slash added explicitly. Do not merge these branches — adding
+    // "file:///" unconditionally double-slashes POSIX paths (file:////...).
+    if (posix.startsWith("/")) {
+      return `file://${posix}`;
+    }
+    return `file:///${posix}`;
   }
   return staticFile(clean);
 }
diff --git a/remotion-composer/src/CollageBurst.tsx b/remotion-composer/src/CollageBurst.tsx
index 3bba2132..b0400095 100644
--- a/remotion-composer/src/CollageBurst.tsx
+++ b/remotion-composer/src/CollageBurst.tsx
@@ -26,7 +26,15 @@ function resolveAsset(src: string): string {
   if (src.startsWith("http://") || src.startsWith("https://") || src.startsWith("data:")) return src;
   const clean = src.replace(/^file:\/\/\/?/, "");
   if (clean.startsWith("/") || /^[A-Za-z]:[\\/]/.test(clean)) {
-    return `file:///${clean.replace(/\\/g, "/")}`;
+    const posix = clean.replace(/\\/g, "/");
+    // POSIX absolute paths already have a leading "/" — file:// + posix
+    // gives exactly three slashes. Windows drive paths (C:/...) need the
+    // extra slash added explicitly. Do not merge these branches — adding
+    // "file:///" unconditionally double-slashes POSIX paths (file:////...).
+    if (posix.startsWith("/")) {
+      return `file://${posix}`;
+    }
+    return `file:///${posix}`;
   }
   return staticFile(clean);
 }
diff --git a/remotion-composer/src/Explainer.tsx b/remotion-composer/src/Explainer.tsx
index fb55dde6..cf7ae03f 100644
--- a/remotion-composer/src/Explainer.tsx
+++ b/remotion-composer/src/Explainer.tsx
@@ -22,7 +22,15 @@ function resolveAsset(src: string): string {
   // Absolute paths (Unix: /foo, Windows: C:\foo or C:/foo) — convert to file:// URI
   // staticFile() only accepts relative paths within public/, so absolute paths must bypass it
   if (clean.startsWith("/") || /^[A-Za-z]:[\\/]/.test(clean)) {
-    return `file:///${clean.replace(/\\/g, "/")}`;
+    const posix = clean.replace(/\\/g, "/");
+    // POSIX absolute paths already have a leading "/" — file:// + posix
+    // gives exactly three slashes. Windows drive paths (C:/...) need the
+    // extra slash added explicitly. Do not merge these branches — adding
+    // "file:///" unconditionally double-slashes POSIX paths (file:////...).
+    if (posix.startsWith("/")) {
+      return `file://${posix}`;
+    }
+    return `file:///${posix}`;
   }
   return staticFile(clean);
 }
diff --git a/remotion-composer/src/LyricOverlay.tsx b/remotion-composer/src/LyricOverlay.tsx
index 24605f57..4896cf1e 100644
--- a/remotion-composer/src/LyricOverlay.tsx
+++ b/remotion-composer/src/LyricOverlay.tsx
@@ -19,7 +19,15 @@ function resolveAsset(src: string): string {
   if (src.startsWith("http://") || src.startsWith("https://") || src.startsWith("data:")) return src;
   const clean = src.replace(/^file:\/\/\/?/, "");
   if (clean.startsWith("/") || /^[A-Za-z]:[\\/]/.test(clean)) {
-    return `file:///${clean.replace(/\\/g, "/")}`;
+    const posix = clean.replace(/\\/g, "/");
+    // POSIX absolute paths already have a leading "/" — file:// + posix
+    // gives exactly three slashes. Windows drive paths (C:/...) need the
+    // extra slash added explicitly. Do not merge these branches — adding
+    // "file:///" unconditionally double-slashes POSIX paths (file:////...).
+    if (posix.startsWith("/")) {
+      return `file://${posix}`;
+    }
+    return `file:///${posix}`;
   }
   return staticFile(clean);
 }
diff --git a/remotion-composer/src/TitledVideo.tsx b/remotion-composer/src/TitledVideo.tsx
index baaa0b8a..0129271c 100644
--- a/remotion-composer/src/TitledVideo.tsx
+++ b/remotion-composer/src/TitledVideo.tsx
@@ -46,7 +46,15 @@ function resolveAsset(src: string): string {
   }
   const clean = src.replace(/^file:\/\/\/?/, "");
   if (clean.startsWith("/") || /^[A-Za-z]:[\\/]/.test(clean)) {
-    return `file:///${clean.replace(/\\/g, "/")}`;
+    const posix = clean.replace(/\\/g, "/");
+    // POSIX absolute paths already have a leading "/" — file:// + posix
+    // gives exactly three slashes. Windows drive paths (C:/...) need the
+    // extra slash added explicitly. Do not merge these branches — adding
+    // "file:///" unconditionally double-slashes POSIX paths (file:////...).
+    if (posix.startsWith("/")) {
+      return `file://${posix}`;
+    }
+    return `file:///${posix}`;
   }
   return staticFile(clean);
 }
diff --git a/remotion-composer/src/components/ScreenshotScene.tsx b/remotion-composer/src/components/ScreenshotScene.tsx
index 89cbc3ff..777f0f19 100644
--- a/remotion-composer/src/components/ScreenshotScene.tsx
+++ b/remotion-composer/src/components/ScreenshotScene.tsx
@@ -90,7 +90,15 @@ function resolveAsset(src: string): string {
   }
   const clean = src.replace(/^file:\/\/\/?/, "");
   if (clean.startsWith("/") || /^[A-Za-z]:[\\/]/.test(clean)) {
-    return `file:///${clean.replace(/\\/g, "/")}`;
+    const posix = clean.replace(/\\/g, "/");
+    // POSIX absolute paths already have a leading "/" — file:// + posix
+    // gives exactly three slashes. Windows drive paths (C:/...) need the
+    // extra slash added explicitly. Do not merge these branches — adding
+    // "file:///" unconditionally double-slashes POSIX paths (file:////...).
+    if (posix.startsWith("/")) {
+      return `file://${posix}`;
+    }
+    return `file:///${posix}`;
   }
   return staticFile(clean);
 }