diff --git a/libImaging/QuantPngQuant.c b/libImaging/QuantPngQuant.c
index 8ae1fa901..aae18b895 100644
--- a/libImaging/QuantPngQuant.c
+++ b/libImaging/QuantPngQuant.c
@@ -35,8 +35,8 @@
 int
 quantize_pngquant(
     Pixel *pixelData,
-    uint32_t width,
-    uint32_t height,
+    int width,
+    int height,
     uint32_t quantPixels,
     Pixel **palette,
     uint32_t *paletteLength,
diff --git a/libImaging/QuantPngQuant.h b/libImaging/QuantPngQuant.h
index dc8dd3cfa..d539a7a0d 100644
--- a/libImaging/QuantPngQuant.h
+++ b/libImaging/QuantPngQuant.h
@@ -4,8 +4,8 @@
 #include "QuantTypes.h"
 
 int quantize_pngquant(Pixel *,
-    uint32_t,
-    uint32_t,
+    int,
+    int,
     uint32_t,
     Pixel **,
     uint32_t *,