diff --git a/core/src/com/google/zxing/qrcode/detector/AlignmentPatternFinder.java b/core/src/com/google/zxing/qrcode/detector/AlignmentPatternFinder.java
index 2f48fa819..88c2caf48 100644
--- a/core/src/com/google/zxing/qrcode/detector/AlignmentPatternFinder.java
+++ b/core/src/com/google/zxing/qrcode/detector/AlignmentPatternFinder.java
@@ -164,7 +164,7 @@ final class AlignmentPatternFinder {
    */
   private boolean foundPatternCross(int[] stateCount) {
     float moduleSize = this.moduleSize;
-    float maxVariance = moduleSize / 2.5f;
+    float maxVariance = moduleSize / 2.0f;
     for (int i = 0; i < 3; i++) {
       if (Math.abs(moduleSize - stateCount[i]) >= maxVariance) {
         return false;
@@ -184,7 +184,7 @@ final class AlignmentPatternFinder {
    * observed in any reading state, based on the results of the horizontal scan
    * @return vertical center of alignment pattern, or {@link Float#NaN} if not found
    */
-  private float crossCheckVertical(int startI, int centerJ, int maxCount) {
+  private float crossCheckVertical(int startI, int centerJ, int maxCount, int originalStateCountTotal) {
     MonochromeBitmapSource image = this.image;
 
     int maxI = image.getHeight();
@@ -225,6 +225,11 @@ final class AlignmentPatternFinder {
       return Float.NaN;
     }
 
+    int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
+    if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {
+      return Float.NaN;
+    }
+
     return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : Float.NaN;
   }
 
@@ -240,8 +245,9 @@ final class AlignmentPatternFinder {
    * @return {@link AlignmentPattern} if we have found the same pattern twice, or null if not
    */
   private AlignmentPattern handlePossibleCenter(int[] stateCount, int i, int j) {
+    int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2];
     float centerJ = centerFromEnd(stateCount, j);
-    float centerI = crossCheckVertical(i, (int) centerJ, 2 * stateCount[1]);
+    float centerI = crossCheckVertical(i, (int) centerJ, 2 * stateCount[1], stateCountTotal);
     if (!Float.isNaN(centerI)) {
       float estimatedModuleSize = (float) (stateCount[0] + stateCount[1] + stateCount[2]) / 3.0f;
       int max = possibleCenters.size();
diff --git a/core/src/com/google/zxing/qrcode/detector/Detector.java b/core/src/com/google/zxing/qrcode/detector/Detector.java
index 87a08fbaf..940476b4a 100644
--- a/core/src/com/google/zxing/qrcode/detector/Detector.java
+++ b/core/src/com/google/zxing/qrcode/detector/Detector.java
@@ -62,14 +62,14 @@ public final class Detector {
     Version provisionalVersion = Version.getProvisionalVersionForDimension(dimension);
     int modulesBetweenFPCenters = provisionalVersion.getDimensionForVersion() - 7;
 
-    // Guess where a "bottom right" finder pattern would have been
-    float bottomRightX = topRight.getX() - topLeft.getX() + bottomLeft.getX();
-    float bottomRightY = topRight.getY() - topLeft.getY() + bottomLeft.getY();
-
     AlignmentPattern alignmentPattern = null;
     // Anything above version 1 has an alignment pattern
     if (provisionalVersion.getAlignmentPatternCenters().length > 0) {
 
+      // Guess where a "bottom right" finder pattern would have been
+      float bottomRightX = topRight.getX() - topLeft.getX() + bottomLeft.getX();
+      float bottomRightY = topRight.getY() - topLeft.getY() + bottomLeft.getY();
+
       // Estimate that alignment pattern is closer by 3 modules
       // from "bottom right" to known top left location
       float correctionToTopLeft = 1.0f - 3.0f / (float) modulesBetweenFPCenters;
diff --git a/core/src/com/google/zxing/qrcode/detector/FinderPatternFinder.java b/core/src/com/google/zxing/qrcode/detector/FinderPatternFinder.java
index c97e8f82f..8b4d99684 100755
--- a/core/src/com/google/zxing/qrcode/detector/FinderPatternFinder.java
+++ b/core/src/com/google/zxing/qrcode/detector/FinderPatternFinder.java
@@ -179,8 +179,8 @@ final class FinderPatternFinder {
       return false;
     }
     float moduleSize = (float) totalModuleSize / 7.0f;
-    float maxVariance = moduleSize / 2.5f;
-    // Allow less than 40% variance from 1-1-3-1-1 proportions
+    float maxVariance = moduleSize / 2.0f;
+    // Allow less than 50% variance from 1-1-3-1-1 proportions
     return Math.abs(moduleSize - stateCount[0]) < maxVariance &&
         Math.abs(moduleSize - stateCount[1]) < maxVariance &&
         Math.abs(3.0f * moduleSize - stateCount[2]) < 3.0f * maxVariance &&
@@ -199,7 +199,7 @@ final class FinderPatternFinder {
    * observed in any reading state, based on the results of the horizontal scan
    * @return vertical center of finder pattern, or {@link Float#NaN} if not found
    */
-  private float crossCheckVertical(int startI, int centerJ, int maxCount) {
+  private float crossCheckVertical(int startI, int centerJ, int maxCount, int originalStateCountTotal) {
     MonochromeBitmapSource image = this.image;
 
     int maxI = image.getHeight();
@@ -254,15 +254,22 @@ final class FinderPatternFinder {
       return Float.NaN;
     }
 
+    // If we found a finder-pattern-like section, but its size is more than 20% different than
+    // the original, assume it's a false positive
+    int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];
+    if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {
+      return Float.NaN;
+    }
+
     return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : Float.NaN;
   }
 
   /**
-   * <p>Like {@link #crossCheckVertical(int, int, int)}, and in fact is basically identical,
+   * <p>Like {@link #crossCheckVertical(int, int, int, int)}, and in fact is basically identical,
    * except it reads horizontally instead of vertically. This is used to cross-cross
    * check a vertical cross check and locate the real center of the alignment pattern.</p>
    */
-  private float crossCheckHorizontal(int startJ, int centerI, int maxCount) {
+  private float crossCheckHorizontal(int startJ, int centerI, int maxCount, int originalStateCountTotal) {
     MonochromeBitmapSource image = this.image;
 
     int maxJ = image.getWidth();
@@ -314,6 +321,13 @@ final class FinderPatternFinder {
       return Float.NaN;
     }
 
+    // If we found a finder-pattern-like section, but its size is significantly different than
+    // the original, assume it's a false positive
+    int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];
+    if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {
+      return Float.NaN;
+    }
+
     return foundPatternCross(stateCount) ? centerFromEnd(stateCount, j) : Float.NaN;
   }
 
@@ -336,14 +350,14 @@ final class FinderPatternFinder {
   private boolean handlePossibleCenter(int[] stateCount,
                                        int i,
                                        int j) {
+    int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];
     float centerJ = centerFromEnd(stateCount, j);
-    float centerI = crossCheckVertical(i, (int) centerJ, stateCount[2]);
+    float centerI = crossCheckVertical(i, (int) centerJ, stateCount[2], stateCountTotal);
     if (!Float.isNaN(centerI)) {
       // Re-cross check
-      centerJ = crossCheckHorizontal((int) centerJ, (int) centerI, stateCount[2]);
+      centerJ = crossCheckHorizontal((int) centerJ, (int) centerI, stateCount[2], stateCountTotal);
       if (!Float.isNaN(centerJ)) {
-        float estimatedModuleSize =
-            (float) (stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4]) / 7.0f;
+        float estimatedModuleSize = (float) stateCountTotal / 7.0f;
         boolean found = false;
         int max = possibleCenters.size();
         for (int index = 0; index < max; index++) {