diff --git a/src/IntPatch/IntPatch_WLine.cxx b/src/IntPatch/IntPatch_WLine.cxx
index e55a3d218f..72bd7bc737 100644
--- a/src/IntPatch/IntPatch_WLine.cxx
+++ b/src/IntPatch/IntPatch_WLine.cxx
@@ -120,7 +120,9 @@ static void RecadreMemePeriode(IntSurf_PntOn2S& POn2S,const IntSurf_PntOn2S& Ref
 }
 
 static Standard_Boolean CompareVertexAndPoint(const gp_Pnt& V, const gp_Pnt& P, const Standard_Real& Tol) { 
-  return (V.Distance(P) <= Tol);
+  const Standard_Real aSQDist = V.SquareDistance(P);
+  const Standard_Real aSQTol = Tol*Tol;
+  return (aSQDist <= aSQTol);
 }
 
 void IntPatch_WLine::SetPeriod(const Standard_Real pu1,
diff --git a/src/IntWalk/IntWalk_IWalking_5.gxx b/src/IntWalk/IntWalk_IWalking_5.gxx
index 98dce89f3e..ca67056f06 100644
--- a/src/IntWalk/IntWalk_IWalking_5.gxx
+++ b/src/IntWalk/IntWalk_IWalking_5.gxx
@@ -107,8 +107,18 @@ IntWalk_StatusDeflection IntWalk_IWalking::TestDeflection
     }
   }
 
-  if (Abs(Du) < tolerance(1) && Abs(Dv) < tolerance(2))
+  const Standard_Real aMinTolU = 0.1*Abs(Step*previousd2d.X()),
+                      aMinTolV = 0.1*Abs(Step*previousd2d.Y());
+
+  if ((Abs(Du) < Min(tolerance(1), aMinTolU)) && (Abs(Dv) < Min(tolerance(2), aMinTolV)))
+  {
+    //Thin shapes (for which Ulast-Ufirst or/and Vlast-Vfirst is quite small)
+    //exists (see bug #25820). In this case, step is quite small too.
+    //Nevertheless, it not always means that we mark time. Therefore, Du and Dv
+    //must consider step (aMinTolU and aMinTolV parameters).
+
     return IntWalk_ArretSurPointPrecedent; //confused point 2d
+  }
 
   Standard_Real Cosi = StepSign * (Du * previousd2d.X() + Dv * previousd2d.Y());
 
diff --git a/tests/bugs/modalg_6/bug25820_1 b/tests/bugs/modalg_6/bug25820_1
new file mode 100644
index 0000000000..7ce786e317
--- /dev/null
+++ b/tests/bugs/modalg_6/bug25820_1
@@ -0,0 +1,43 @@
+puts "========"
+puts "OCC25820"
+puts "========"
+puts ""
+###################################################################
+# No Intersection Curves between surface of revolution and planes
+###################################################################
+
+restore [locate_data_file OCC25820-Revolution_5.brep] b1
+explode b1 f
+copy b1_4 b1
+
+restore [locate_data_file OCC25820-Translation_1.brep] b2
+explode b2 f
+copy b2_2 b2
+
+smallview
+clear
+display b1
+display b2
+fit
+
+dlog reset
+dlog on
+decho off
+bopcurves b1 b2
+decho on
+set bug_info [dlog get]
+
+set bug_info [string trim [string range $bug_info [expr {[string first "\n" $bug_info] + 1}] [expr {[string last "\n" $bug_info] - 1}]]]
+set bug_info_tol [string trim [string range $bug_info [expr {[string first "=" $bug_info] + 1}] [expr {[string first "\n" $bug_info] - 1}]]]
+set bug_info_cur [string trim [string range $bug_info [expr {[string first "\n" $bug_info] + 1}] [expr {[string length $bug_info] - 1}]]]
+set bug_info_cur [string trim [string range $bug_info_cur 0 [expr {[string first " " $bug_info_cur] - 1}]]]
+
+if {$bug_info_tol > 1.0e-7} {
+  puts "ERROR: OCC25820 is reproduced. Tolerance is to large ($bug_info_tol)."
+}
+
+if {$bug_info_cur != 1} {
+  puts "ERROR: OCC25820 is reproduced. Too many curves were found."
+}
+
+set only_screen_axo 1
diff --git a/tests/bugs/modalg_6/bug25820_2 b/tests/bugs/modalg_6/bug25820_2
new file mode 100644
index 0000000000..53c72e4dcf
--- /dev/null
+++ b/tests/bugs/modalg_6/bug25820_2
@@ -0,0 +1,43 @@
+puts "========"
+puts "OCC25820"
+puts "========"
+puts ""
+###################################################################
+# No Intersection Curves between surface of revolution and planes
+###################################################################
+
+restore [locate_data_file OCC25820-Revolution_5.brep] b1
+explode b1 f
+copy b1_4 b1
+
+restore [locate_data_file OCC25820-Translation_2.brep] b2
+explode b2 f
+copy b2_4 b2
+
+smallview
+clear
+display b1
+display b2
+fit
+
+dlog reset
+dlog on
+decho off
+bopcurves b1 b2
+decho on
+set bug_info [dlog get]
+
+set bug_info [string trim [string range $bug_info [expr {[string first "\n" $bug_info] + 1}] [expr {[string last "\n" $bug_info] - 1}]]]
+set bug_info_tol [string trim [string range $bug_info [expr {[string first "=" $bug_info] + 1}] [expr {[string first "\n" $bug_info] - 1}]]]
+set bug_info_cur [string trim [string range $bug_info [expr {[string first "\n" $bug_info] + 1}] [expr {[string length $bug_info] - 1}]]]
+set bug_info_cur [string trim [string range $bug_info_cur 0 [expr {[string first " " $bug_info_cur] - 1}]]]
+
+if {$bug_info_tol > 1.0e-7} {
+  puts "ERROR: OCC25820 is reproduced. Tolerance is to large ($bug_info_tol)."
+}
+
+if {$bug_info_cur != 1} {
+  puts "ERROR: OCC25820 is reproduced. Too many curves were found."
+}
+
+set only_screen_axo 1
diff --git a/tests/bugs/modalg_6/bug25820_3 b/tests/bugs/modalg_6/bug25820_3
new file mode 100644
index 0000000000..216675f0cf
--- /dev/null
+++ b/tests/bugs/modalg_6/bug25820_3
@@ -0,0 +1,43 @@
+puts "========"
+puts "OCC25820"
+puts "========"
+puts ""
+###################################################################
+# No Intersection Curves between surface of revolution and planes
+###################################################################
+
+restore [locate_data_file OCC25820-Revolution_5.brep] b1
+explode b1 f
+copy b1_4 b1
+
+restore [locate_data_file OCC25820-Translation_3.brep] b2
+explode b2 f
+copy b2_3 b2
+
+smallview
+clear
+display b1
+display b2
+fit
+
+dlog reset
+dlog on
+decho off
+bopcurves b1 b2
+decho on
+set bug_info [dlog get]
+
+set bug_info [string trim [string range $bug_info [expr {[string first "\n" $bug_info] + 1}] [expr {[string last "\n" $bug_info] - 1}]]]
+set bug_info_tol [string trim [string range $bug_info [expr {[string first "=" $bug_info] + 1}] [expr {[string first "\n" $bug_info] - 1}]]]
+set bug_info_cur [string trim [string range $bug_info [expr {[string first "\n" $bug_info] + 1}] [expr {[string length $bug_info] - 1}]]]
+set bug_info_cur [string trim [string range $bug_info_cur 0 [expr {[string first " " $bug_info_cur] - 1}]]]
+
+if {$bug_info_tol > 1.0e-7} {
+  puts "ERROR: OCC25820 is reproduced. Tolerance is to large ($bug_info_tol)."
+}
+
+if {$bug_info_cur != 1} {
+  puts "ERROR: OCC25820 is reproduced. Too many curves were found."
+}
+
+set only_screen_axo 1