diff --git a/cmd/Makefile b/cmd/Makefile
index 54be081..d2985bb 100644
--- a/cmd/Makefile
+++ b/cmd/Makefile
@@ -31,6 +31,7 @@ dev: out/stretch
 	out/stretch --time=0.8 --semitones=10 $(TEST_WAV) out/shift.wav
 	out/stretch --time=0.8 --semitones=10 --formant-comp $(TEST_WAV) out/shift-fc.wav
 	out/stretch --time=0.8 --semitones=10 --formant-comp --formant=3 $(TEST_WAV) out/shift-fc-f3.wav
+	out/stretch --time=0.8 --semitones=10 --formant-comp --formant=3 --formant-base=500 $(TEST_WAV) out/shift-fc-f3-fb500.wav
 
 clean:
 	rm -rf out
diff --git a/cmd/main.cpp b/cmd/main.cpp
index 47dad4d..3a1f2b1 100644
--- a/cmd/main.cpp
+++ b/cmd/main.cpp
@@ -76,6 +76,7 @@ int main(int argc, char* argv[]) {
 	double semitones = args.flag<double>("semitones", "pitch-shift amount", 0);
 	double formants = args.flag<double>("formant", "formant-shift amount (semitones)", 0);
 	bool formantComp = args.hasFlag("formant-comp", "formant compensation");
+	double formantBase = args.flag<double>("formant-base", "formant base frequency (Hz, 0=auto)", 0);
 	double tonality = args.flag<double>("tonality", "tonality limit (Hz)", 8000);
 	double time = args.flag<double>("time", "time-stretch factor", 1);
 	bool exactLength = args.hasFlag("exact", "trims the start/end so the output has the correct length");
@@ -112,6 +113,7 @@ int main(int argc, char* argv[]) {
 	stretch.presetDefault(int(inWav.channels), inWav.sampleRate, splitComputation);
 	stretch.setTransposeSemitones(semitones, tonality/inWav.sampleRate);
 	stretch.setFormantSemitones(formants, formantComp);
+	stretch.setFormantBase(formantBase/inWav.sampleRate);
 	double initSeconds = stopwatch.lap();
 
 	initMemory = initMemory.diff();
diff --git a/signalsmith-stretch.h b/signalsmith-stretch.h
index 6d68040..da98cef 100644
--- a/signalsmith-stretch.h
+++ b/signalsmith-stretch.h
@@ -120,6 +120,10 @@ struct SignalsmithStretch {
 	void setFormantSemitones(Sample semitones, bool compensatePitch=false) {
 		setFormantFactor(std::pow(2, semitones/12), compensatePitch);
 	}
+	// 0 means attempting to detect the pitch
+	void setFormantBase(Sample baseFreq=0) {
+		formantBaseFreq = baseFreq;
+	}
 
 	// Provide previous input ("pre-roll"), without affecting the speed calculation.  You should ideally feed it one block-length + one interval
 	template<class Inputs>
@@ -826,6 +830,7 @@ private:
 	Sample freqEstimateWeight = 0;
 	
 	std::vector<Sample> formantMetric;
+	Sample formantBaseFreq = 0;
 	void updateFormants(size_t) {
 		for (auto &e : formantMetric) e = 0;
 		for (int c = 0; c < channels; ++c) {
@@ -834,42 +839,46 @@ private:
 				formantMetric[b] += bins[b].inputEnergy;
 			}
 		}
-		
-		// 3 highest peaks in the input
-		std::array<int, 3> peakIndices{0, 0, 0};
-		for (int b = 1; b < bands - 1; ++b) {
-			Sample e = formantMetric[b];
-			// local maxima only
-			if (e < formantMetric[b - 1] || e <= formantMetric[b + 1]) continue;
-			
-			if (e > formantMetric[peakIndices[0]]) {
-				if (e > formantMetric[peakIndices[1]]) {
-					if (e > formantMetric[peakIndices[2]]) {
-						peakIndices = {peakIndices[1], peakIndices[2], b};
+
+		Sample freqEstimate = freqToBand(formantBaseFreq);
+		if (formantBaseFreq <= 0) {
+			// 3 highest peaks in the input
+			std::array<int, 3> peakIndices{0, 0, 0};
+			for (int b = 1; b < bands - 1; ++b) {
+				Sample e = formantMetric[b];
+				// local maxima only
+				if (e < formantMetric[b - 1] || e <= formantMetric[b + 1]) continue;
+				
+				if (e > formantMetric[peakIndices[0]]) {
+					if (e > formantMetric[peakIndices[1]]) {
+						if (e > formantMetric[peakIndices[2]]) {
+							peakIndices = {peakIndices[1], peakIndices[2], b};
+						} else {
+							peakIndices = {peakIndices[1], b, peakIndices[2]};
+						}
 					} else {
-						peakIndices = {peakIndices[1], b, peakIndices[2]};
+						peakIndices[0] = b;
 					}
-				} else {
-					peakIndices[0] = b;
 				}
 			}
-		}
-		
-		// VERY rough pitch estimation
-		int peakEstimate = peakIndices[2];
-		if (formantMetric[peakIndices[1]] > formantMetric[peakIndices[2]]*0.1) {
-			int diff = std::abs(peakEstimate - peakIndices[1]);
-			if (diff > peakEstimate/8 && diff < peakEstimate*7/8) peakEstimate = peakEstimate%diff;
-			if (formantMetric[peakIndices[0]] > formantMetric[peakIndices[2]]*0.01) {
-				int diff = std::abs(peakEstimate - peakIndices[0]);
+			
+			// VERY rough pitch estimation
+			int peakEstimate = peakIndices[2];
+			if (formantMetric[peakIndices[1]] > formantMetric[peakIndices[2]]*0.1) {
+				int diff = std::abs(peakEstimate - peakIndices[1]);
 				if (diff > peakEstimate/8 && diff < peakEstimate*7/8) peakEstimate = peakEstimate%diff;
+				if (formantMetric[peakIndices[0]] > formantMetric[peakIndices[2]]*0.01) {
+					int diff = std::abs(peakEstimate - peakIndices[0]);
+					if (diff > peakEstimate/8 && diff < peakEstimate*7/8) peakEstimate = peakEstimate%diff;
+				}
 			}
+			Sample weight = formantMetric[peakIndices[2]];
+			// Smooth it out a bit
+			freqEstimateWeighted += (peakEstimate*weight - freqEstimateWeighted)*0.25;
+			freqEstimateWeight += (weight - freqEstimateWeight)*0.25;
+			
+			freqEstimate = freqEstimateWeighted/(freqEstimateWeight + Sample(1e-30));
 		}
-		Sample weight = formantMetric[peakIndices[2]];
-		// Smooth it out a bit
-		freqEstimateWeighted += (peakEstimate*weight - freqEstimateWeighted)*0.25;
-		freqEstimateWeight += (weight - freqEstimateWeight)*0.25;
-		Sample freqEstimate = freqEstimateWeighted/(freqEstimateWeight + Sample(1e-30));
 	
 		for (int b = 0; b < bands; ++b) {
 			formantMetric[b] = std::sqrt(std::sqrt(formantMetric[b]));