diff --git a/src/IntPatch/IntPatch_WLineTool.cxx b/src/IntPatch/IntPatch_WLineTool.cxx
index f3200190ac..d0730fbd53 100644
--- a/src/IntPatch/IntPatch_WLineTool.cxx
+++ b/src/IntPatch/IntPatch_WLineTool.cxx
@@ -1643,7 +1643,7 @@ void IntPatch_WLineTool::JoinWLines(IntPatch_SequenceOfLine& theSlin,
                                            aWLine2->Point(aNbPntsWL2 - 1);
 
       if (!CheckArgumentsToJoin(theS1, theS2, aPntLWL1, aPt1.Value(),
-                                aPntFWL1.Value(), aPt2.Value(), aMinRad))
+                                aPntLWL1.Value(), aPt2.Value(), aMinRad))
       {
         continue;
       }
diff --git a/tests/bugs/modalg_7/bug31850_1 b/tests/bugs/modalg_7/bug31850_1
new file mode 100644
index 0000000000..906267109f
--- /dev/null
+++ b/tests/bugs/modalg_7/bug31850_1
@@ -0,0 +1,47 @@
+puts "======================================================="
+puts "0031850: Modeling Algorithms - boolean cut and common generate unexpected result"
+puts "======================================================="
+puts ""
+
+restore [locate_data_file bug31850.brep] s
+explode s
+
+bclearobjects
+bcleartools
+baddobjects s_1
+baddtools s_2
+bfillds
+
+bbop r0 0
+bbop r1 1
+bbop r2 2
+bbop r3 3
+bbop r4 4
+bbuild rgf
+
+foreach r {r0 r1 r2 r3 r4 rgf} {
+  checkshape $r
+  if {![regexp "OK" [bopcheck $r]]} {
+    puts "Error: the $r is a self-interfering shape"
+  }
+}
+
+checknbshapes r0 -wire 28 -face 28 -shell 1 -solid 1 -t
+checkprops r0 -s 1107.94 -v 472.151
+
+checknbshapes r1 -wire 50 -face 45 -shell 1 -solid 1 -t
+checkprops r1 -s 14959.7 -v 37939.8
+
+checknbshapes r2 -wire 33 -face 28 -shell 1 -solid 1 -t
+checkprops r2 -s 5244.61 -v 2516.56
+
+checknbshapes r3 -wire 45 -face 45 -shell 1 -solid 1 -t
+checkprops r3 -s 10823 -v 34951.1
+
+checkprops r4 -l 203.491
+checksection r4 -r 10
+
+checknbshapes rgf -wire 78 -face 73 -shell 3 -solid 3 -t
+checkprops rgf -s 17175.6 -v 37939.8
+
+checkview -display r0 -2d -path ${imagedir}/${test_image}.png
diff --git a/tests/bugs/modalg_7/bug31850_2 b/tests/bugs/modalg_7/bug31850_2
new file mode 100644
index 0000000000..07312180d6
--- /dev/null
+++ b/tests/bugs/modalg_7/bug31850_2
@@ -0,0 +1,54 @@
+puts "======================================================="
+puts "0031850: Modeling Algorithms - boolean cut and common generate unexpected result"
+puts "======================================================="
+puts ""
+
+restore [locate_data_file bug31850.brep] s
+explode s
+
+bfuzzyvalue 1.e-6
+bnondestructive 1
+brunparallel 1
+setfillhistory 0
+
+bclearobjects
+bcleartools
+baddobjects s_1
+baddtools s_2
+bfillds
+
+bbop r0 0
+bbop r1 1
+bbop r2 2
+bbop r3 3
+bbop r4 4
+bbuild rgf
+
+boptions -default
+
+foreach r {r0 r1 r2 r3 r4 rgf} {
+  checkshape $r
+  if {![regexp "OK" [bopcheck $r]]} {
+    puts "Error: the $r is a self-interfering shape"
+  }
+}
+
+checknbshapes r0 -wire 28 -face 28 -shell 1 -solid 1 -t
+checkprops r0 -s 1107.94 -v 472.151
+
+checknbshapes r1 -wire 50 -face 45 -shell 1 -solid 1 -t
+checkprops r1 -s 14959.7 -v 37939.8
+
+checknbshapes r2 -wire 33 -face 28 -shell 1 -solid 1 -t
+checkprops r2 -s 5244.61 -v 2516.56
+
+checknbshapes r3 -wire 45 -face 45 -shell 1 -solid 1 -t
+checkprops r3 -s 10823 -v 34951.1
+
+checkprops r4 -l 203.491
+checksection r4 -r 10
+
+checknbshapes rgf -wire 78 -face 73 -shell 3 -solid 3 -t
+checkprops rgf -s 17175.6 -v 37939.8
+
+checkview -display r0 -2d -path ${imagedir}/${test_image}.png