diff --git a/include/valijson/constraints/concrete_constraints.hpp b/include/valijson/constraints/concrete_constraints.hpp
index 536f7ed..8ba30e2 100644
--- a/include/valijson/constraints/concrete_constraints.hpp
+++ b/include/valijson/constraints/concrete_constraints.hpp
@@ -19,6 +19,7 @@
 #include <set>
 #include <string>
 #include <vector>
+#include <cmath>
 
 #include <valijson/constraints/basic_constraint.hpp>
 #include <valijson/internal/custom_allocator.hpp>
@@ -784,6 +785,11 @@ public:
 
     void setDivisor(double newValue)
     {
+        if (!std::isfinite(newValue) || newValue <= 0.0) {
+            throwRuntimeError(
+                "Divisor for 'multipleOf' or 'divisibleBy' must be positive");
+        }
+
         m_value = newValue;
     }
 
@@ -813,6 +819,11 @@ public:
 
     void setDivisor(int64_t newValue)
     {
+        if (newValue <= 0) {
+            throwRuntimeError(
+                "Divisor for 'multipleOf' or 'divisibleBy' must be positive");
+        }
+
         m_value = newValue;
     }