diff --git a/solve.c b/solve.c
index ba9c90a..f17ae60 100644
--- a/solve.c
+++ b/solve.c
@@ -20,106 +20,98 @@
 
 #include <stdio.h>
 
+static void setpval(struct sudoku *sud, unsigned r, unsigned c, uint16_t pval)
+{
+	for (unsigned val = 0; val < NDIGITS; ++val) {
+		if (pval & 1) {
+			update(sud, r, c, val);
+			return;
+		}
+		pval >>= 1;
+	}
+}
+
 int solve(struct sudoku *sud)
 {
-	unsigned r, c, n, i, j, val, np, pr, pc;
+	unsigned r, c, n, i, j, val, sr, sc;
 	bool match;
 	uint16_t valmask, pvals;
 
 	for (n = 0;; ++n) {
 		match = false;
 
-		/* Check if only one place a value can go on each row. */
-		for (r = 0; r < NDIGITS; ++r) {
-			for (val = 0; val < NDIGITS; ++val) {
-				valmask = 1 << val;
-
-				np = 0;
-				for (c = 0; c < NDIGITS; ++c) {
-					if (!(sud->cells[r][c] & DETMASK)
-					    && sud->cells[r][c] & valmask) {
-						pr = r;
-						pc = c;
-						++np;
-						if (np > 1)
-							break;
-					}
-				}
-				if (np == 1) {
-					if (update(sud, pr, pc, val) != OK)
-						return -1;
-					match = true;
-				}
-			}
-		}
-
-		/* Check if only one place a value can go on each column. */
-		for (c = 0; c < NDIGITS; ++c) {
-			for (val = 0; val < NDIGITS; ++val) {
-				valmask = 1 << val;
-
-				np = 0;
-				for (r = 0; r < NDIGITS; ++r) {
-					if (!(sud->cells[r][c] & DETMASK)
-					    && sud->cells[r][c] & valmask) {
-						pr = r;
-						pc = c;
-						++np;
-						if (np > 1)
-							break;
-					}
-				}
-				if (np == 1) {
-					if (update(sud, pr, pc, val) != OK)
-						return -1;
-					match = true;
-				}
-			}
-		}
-
-		/* Check if only one place a value can go in each segment. */
-		for (i = 0; i < NDIGITS; ++i) {
-			for (val = 0; val < NDIGITS; ++val) {
-				valmask = 1 << val;
-
-				np = 0;
-				for (j = 0; j < NDIGITS; ++j) {
-					r = SEGLEN * (i / SEGLEN) + j / SEGLEN;
-					c = SEGLEN * (i % SEGLEN) + j % SEGLEN;
-					if (!(sud->cells[r][c] & DETMASK)
-					    && sud->cells[r][c] & valmask) {
-						pr = r;
-						pc = c;
-						++np;
-						if (np > 1)
-							break;
-					}
-				}
-				if (np == 1) {
-					if (update(sud, pr, pc, val) != OK)
-						return -1;
-					match = true;
-				}
-			}
-		}
-
-		/* Check each cell for if it has only one possible value. */
 		for (r = 0; r < NDIGITS; ++r) {
 			for (c = 0; c < NDIGITS; ++c) {
 				if (DET(sud->cells[r][c]))
 					continue;
 
+				/*
+				 * Check if there's only one possible value this cell
+				 * can have.
+				 */
 				pvals = sud->cells[r][c] & PVALSMASK;
 				for (val = 0; val < NDIGITS; ++val) {
 					if (pvals & 1) {
 						if (pvals == 1) {
 							update(sud, r, c, val);
 							match = true;
+							goto next_cell;
 						}
 						break;
 					}
 					pvals >>= 1;
 				}
+
+				/*
+				 * Check if there's a possible value unique to this
+				 * cell in its row.
+				 */
+				valmask = 0;
+				for (i = 0; i < NDIGITS; ++i) {
+					if (i != r && !DET(sud->cells[i][c]))
+						valmask |= sud->cells[i][c];
+				}
+				if ((pvals = sud->cells[r][c] & ~valmask)) {
+					setpval(sud, r, c, pvals);
+					match = true;
+					continue;
+				}
+
+				/*
+				 * Check if there's a possible value unique to this
+				 * cell in its column.
+				 */
+				valmask = 0;
+				for (i = 0; i < NDIGITS; ++i) {
+					if (i != c && !DET(sud->cells[r][i]))
+						valmask |= sud->cells[r][i];
+				}
+				if ((pvals = sud->cells[r][c] & ~valmask)) {
+					setpval(sud, r, c, pvals);
+					match = true;
+					continue;
+				}
+
+				/*
+				 * Check if there's a possible value unique to this
+				 * cell in its segment.
+				 */
+				sr = SEGLEN * (r / SEGLEN);
+				sc = SEGLEN * (c / SEGLEN);
+				valmask = 0;
+				for (i = sr; i < sr + SEGLEN; ++i) {
+					for (j = sc; j < sc + SEGLEN; ++j) {
+						if ((i != r || j != c) && !DET(sud->cells[i][j]))
+							valmask |= sud->cells[i][j];
+					}
+				}
+				if ((pvals = sud->cells[r][c] & ~valmask)) {
+					setpval(sud, r, c, pvals);
+					match = true;
+					continue;
+				}
+
+			next_cell:;
 			}
 		}