diff --git a/kmeans.c b/kmeans.c
index 7ee273d..c8630ae 100644
--- a/kmeans.c
+++ b/kmeans.c
@@ -73,8 +73,13 @@ LIQ_PRIVATE double kmeans_do_iteration(histogram *hist, colormap *const map, kme
     const int hist_size = hist->size;
 
     double total_diff=0;
+#if __GNUC__ >= 9
+    #pragma omp parallel for if (hist_size > 2000) \
+        schedule(static) default(none) shared(achv,average_color,callback,hist_size,map,n) reduction(+:total_diff)
+#else
     #pragma omp parallel for if (hist_size > 2000) \
         schedule(static) default(none) shared(average_color,callback) reduction(+:total_diff)
+#endif
     for(int j=0; j < hist_size; j++) {
         float diff;
         unsigned int match = nearest_search(n, &achv[j].acolor, achv[j].tmp.likely_colormap_index, &diff);
diff --git a/libimagequant.c b/libimagequant.c
index 3506564..114e5f1 100644
--- a/libimagequant.c
+++ b/libimagequant.c
@@ -1276,8 +1276,13 @@ LIQ_NONNULL static float remap_to_palette(liq_image *const input_image, unsigned
     LIQ_ARRAY(kmeans_state, average_color, (KMEANS_CACHE_LINE_GAP+map->colors) * max_threads);
     kmeans_init(map, max_threads, average_color);
 
+#if __GNUC__ >= 9
+    #pragma omp parallel for if (rows*cols > 3000) \
+        schedule(static) default(none) shared(acolormap,average_color,cols,input_image,map,n,output_pixels,rows,transparent_index) reduction(+:remapping_error)
+#else
     #pragma omp parallel for if (rows*cols > 3000) \
         schedule(static) default(none) shared(acolormap) shared(average_color) reduction(+:remapping_error)
+#endif
     for(int row = 0; row < rows; ++row) {
         const f_pixel *const row_pixels = liq_image_get_row_f(input_image, row);
         const f_pixel *const bg_pixels = input_image->background && acolormap[transparent_index].acolor.a < 1.f/256.f ? liq_image_get_row_f(input_image->background, row) : NULL;
diff --git a/mediancut.c b/mediancut.c
index 447a4af..4421cb4 100644
--- a/mediancut.c
+++ b/mediancut.c
@@ -195,8 +195,13 @@ static double prepare_sort(struct box *b, hist_item achv[])
 
     const unsigned int ind1 = b->ind;
     const unsigned int colors = b->colors;
+#if __GNUC__ >= 9
+    #pragma omp parallel for if (colors > 25000) \
+        schedule(static) default(none) shared(achv, channels, colors, ind1)
+#else
     #pragma omp parallel for if (colors > 25000) \
         schedule(static) default(none) shared(achv, channels)
+#endif
     for(unsigned int i=0; i < colors; i++) {
         const float *chans = (const float *)&achv[ind1 + i].acolor;
         // Only the first channel really matters. When trying median cut many times