diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index cfcd72660..a1eadd926 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -3966,7 +3966,7 @@ bool Tokenizer::simplifyKnownVariables()
                         ret = true;
                     }
 
-                    if (Token::Match(tok3->next(), "++|-- %varid%", varid) &&
+                    if (Token::Match(tok3->next(), "++|-- %varid%", varid) && MathLib::isInt(value) &&
                         !Token::Match(tok3->tokAt(3), "[.[]"))
                     {
                         incdec(value, tok3->strAt(1));
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index 003ca427c..4eeadad15 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -89,6 +89,7 @@ private:
         TEST_CASE(simplifyKnownVariables15);
         TEST_CASE(simplifyKnownVariables16);
         TEST_CASE(simplifyKnownVariables17);
+        TEST_CASE(simplifyKnownVariables18);
 
         TEST_CASE(match1);
 
@@ -957,6 +958,14 @@ private:
             simplifyKnownVariables(code));
     }
 
+    void simplifyKnownVariables18()
+    {
+        const char code[] = "void f ( ) { char *s = malloc(100);mp_ptr p = s; ++p; }";
+        ASSERT_EQUALS(
+            "void f ( ) { char * s ; s = malloc ( 100 ) ; mp_ptr p ; p = s ; ++ p ; }",
+            simplifyKnownVariables(code));
+    }
+
     void match1()
     {
         // Match "%var% | %var%"