diff --git a/src/Extrema/Extrema_ExtElCS.cxx b/src/Extrema/Extrema_ExtElCS.cxx
index 6eaac112b8..96384d0cb3 100644
--- a/src/Extrema/Extrema_ExtElCS.cxx
+++ b/src/Extrema/Extrema_ExtElCS.cxx
@@ -361,9 +361,9 @@ void Extrema_ExtElCS::Perform(const gp_Circ& C,
       // Check whether two objects have intersection points
       IntAna_Quadric aCylQuad(S);
       IntAna_IntConicQuad aCircCylInter(C, aCylQuad);
-      Standard_Integer aNbInter = aCircCylInter.NbPoints();
-      if (!aCircCylInter.IsDone())
-        aNbInter = 0;
+      Standard_Integer aNbInter = 0;
+      if (aCircCylInter.IsDone())
+        aNbInter = aCircCylInter.NbPoints();
 
       // Compute the extremas.
       myNbExt  =     2*aNbExt + aNbInter;
diff --git a/tests/bugs/moddata_3/bug25810 b/tests/bugs/moddata_3/bug25810
new file mode 100644
index 0000000000..55ffa8081e
--- /dev/null
+++ b/tests/bugs/moddata_3/bug25810
@@ -0,0 +1,15 @@
+puts "============"
+puts "OCC25810"
+puts "============"
+puts ""
+#######################################################################
+# Exception in extrema operation.
+#######################################################################
+
+restore [locate_data_file bug25810_e1.brep] b1
+restore [locate_data_file bug25810_f1.brep] b2
+
+mkcurve c1 b1
+mksurface s2 b2
+
+extrema c1 s2