diff --git a/ext/bcmath/libbcmath/src/div.c b/ext/bcmath/libbcmath/src/div.c
index e9377fcfc4279..ce9ae1e1dd792 100644
--- a/ext/bcmath/libbcmath/src/div.c
+++ b/ext/bcmath/libbcmath/src/div.c
@@ -427,6 +427,9 @@ bool bc_divide(bc_num numerator, bc_num divisor, bc_num *quot, size_t scale)
 		return true;
 	}
 
+	/* Length of numerator data that can be read */
+	size_t numerator_readable_len = numeratorend - numeratorptr + 1;
+
 	/* set scale to numerator */
 	if (numerator_scale > scale) {
 		size_t scale_diff = numerator_scale - scale;
@@ -434,7 +437,13 @@ bool bc_divide(bc_num numerator, bc_num divisor, bc_num *quot, size_t scale)
 			numerator_bottom_extension -= scale_diff;
 		} else {
 			numerator_bottom_extension = 0;
-			numeratorend -= scale_diff > numerator_top_extension ? scale_diff - numerator_top_extension : 0;
+			if (EXPECTED(numerator_readable_len > scale_diff)) {
+				numerator_readable_len -= scale_diff;
+				numeratorend -= scale_diff;
+			} else {
+				numerator_readable_len = 0;
+				numeratorend = numeratorptr;
+			}
 		}
 		numerator_top_extension = MIN(numerator_top_extension, scale);
 	} else {
@@ -442,9 +451,6 @@ bool bc_divide(bc_num numerator, bc_num divisor, bc_num *quot, size_t scale)
 	}
 	numerator_scale = scale;
 
-	/* Length of numerator data that can be read */
-	size_t numerator_readable_len = numeratorend - numeratorptr + 1;
-
 	if (divisor_len > numerator_readable_len + numerator_bottom_extension) {
 		*quot = bc_copy_num(BCG(_zero_));
 		return true;
diff --git a/ext/bcmath/tests/gh17275.phpt b/ext/bcmath/tests/gh17275.phpt
new file mode 100644
index 0000000000000..c5be97bdaa884
--- /dev/null
+++ b/ext/bcmath/tests/gh17275.phpt
@@ -0,0 +1,14 @@
+--TEST--
+GH-17275 Incorrect result of bcdiv function
+--EXTENSIONS--
+bcmath
+--FILE--
+<?php
+var_dump(
+    bcdiv('0.03772321', '9650.0', 8),
+    bcdiv('0.03772321', '9650.0', 9),
+);
+?>
+--EXPECT--
+string(10) "0.00000390"
+string(11) "0.000003909"