diff --git a/include/libcamera/internal/software_isp/swisp_stats.h b/include/libcamera/internal/software_isp/swisp_stats.h
index d9d0d9b..7f4e457 100644
--- a/include/libcamera/internal/software_isp/swisp_stats.h
+++ b/include/libcamera/internal/software_isp/swisp_stats.h
@@ -28,9 +28,18 @@ struct SwIspStats {
 	 */
 	bool valid;
 	/**
-	 * \brief Sums of colour channels of all the sampled pixels
+	 * \brief Sums of colour channels of the sampled pixels that are not
+	 *        clipped
 	 */
 	RGB<uint64_t> sum_;
+	/**
+	 * \brief Number of pixels added up in sum_
+	 *
+	 * A pixel with any colour channel at or near the top of the range is
+	 * left out of sum_: it reads the same in all channels whatever its
+	 * real colour, and would pull white balance towards grey.
+	 */
+	uint64_t sumPixels;
 	/**
 	 * \brief Number of bins in the yHistogram
 	 */
diff --git a/src/ipa/softisp/algorithms/awb.cpp b/src/ipa/softisp/algorithms/awb.cpp
index 55fd326..71f6997 100644
--- a/src/ipa/softisp/algorithms/awb.cpp
+++ b/src/ipa/softisp/algorithms/awb.cpp
@@ -7,7 +7,6 @@
 
 #include "awb.h"
 
-#include <numeric>
 #include <stdint.h>
 
 #include <libcamera/base/log.h>
@@ -115,10 +114,10 @@ void Awb::prepare(IPAContext &context,
 SoftIspAwbStats Awb::calculateRgbMeans(IPAContext &context,
 				       const SwIspStats *stats) const
 {
-	if (!stats->valid)
+	/* With every pixel clipped, return no means and keep the last gains. */
+	if (!stats->valid || !stats->sumPixels)
 		return {};
 
-	const SwIspStats::Histogram &histogram = stats->yHistogram;
 	const uint8_t blackLevel = context.activeState.blc.level;
 
 	/*
@@ -126,8 +125,7 @@ SoftIspAwbStats Awb::calculateRgbMeans(IPAContext &context,
 	 * would be off if they were computed from the whole brightness range
 	 * rather than from the sensor range.
 	 */
-	const uint64_t nPixels = std::accumulate(
-		histogram.begin(), histogram.end(), uint64_t(0));
+	const uint64_t nPixels = stats->sumPixels;
 	const uint64_t offset = blackLevel * nPixels;
 	const uint64_t minValid = 1;
 
diff --git a/src/libcamera/software_isp/swstats_cpu.cpp b/src/libcamera/software_isp/swstats_cpu.cpp
index 7fb77ce..996223c 100644
--- a/src/libcamera/software_isp/swstats_cpu.cpp
+++ b/src/libcamera/software_isp/swstats_cpu.cpp
@@ -177,12 +177,22 @@ static constexpr unsigned int kBlueYMul = 29; /* 0.114 * 256 */
                                           \
 	uint64_t sumR = 0;                \
 	uint64_t sumG = 0;                \
-	uint64_t sumB = 0;
+	uint64_t sumB = 0;                \
+	uint64_t sumN = 0;
 
+/*
+ * Leave clipped pixels, with any channel at 250 of 255 or above, out of the
+ * colour sums.
+ */
 #define SWSTATS_ACCUMULATE_LINE_STATS(div) \
-	sumR += r;                         \
-	sumG += g;                         \
-	sumB += b;                         \
+	if (r < 250 * (div) &&             \
+	    g < 250 * (div) &&             \
+	    b < 250 * (div)) {             \
+		sumR += r;                 \
+		sumG += g;                 \
+		sumB += b;                 \
+		sumN++;                    \
+	}                                  \
                                            \
 	yVal = r * kRedYMul;               \
 	yVal += g * kGreenYMul;            \
@@ -192,7 +202,8 @@ static constexpr unsigned int kBlueYMul = 29; /* 0.114 * 256 */
 #define SWSTATS_FINISH_LINE_STATS() \
 	stats.sum_.r() += sumR;     \
 	stats.sum_.g() += sumG;     \
-	stats.sum_.b() += sumB;
+	stats.sum_.b() += sumB;     \
+	stats.sumPixels += sumN;
 
 void SwStatsCpu::statsBGGR8Line0(const uint8_t *src[], SwIspStats &stats)
 {
@@ -391,6 +402,7 @@ void SwStatsCpu::startFrame(uint32_t frame)
 
 	for (auto &s : stats_) {
 		s.sum_ = RGB<uint64_t>({ 0, 0, 0 });
+		s.sumPixels = 0;
 		s.yHistogram.fill(0);
 	}
 }
@@ -408,9 +420,11 @@ void SwStatsCpu::finishFrame(uint32_t frame, uint32_t bufferId)
 
 	if (valid) {
 		sharedStats_->sum_ = RGB<uint64_t>({ 0, 0, 0 });
+		sharedStats_->sumPixels = 0;
 		sharedStats_->yHistogram.fill(0);
 		for (const auto &s : stats_) {
 			sharedStats_->sum_ += s.sum_;
+			sharedStats_->sumPixels += s.sumPixels;
 			for (unsigned int j = 0; j < SwIspStats::kYHistogramSize; j++)
 				sharedStats_->yHistogram[j] += s.yHistogram[j];
 		}