diff --git a/src/commonMain/kotlin/com/notkamui/keval/AbstractSyntaxTree.kt b/src/commonMain/kotlin/com/notkamui/keval/AbstractSyntaxTree.kt
index 48c0cf0..efefa72 100644
--- a/src/commonMain/kotlin/com/notkamui/keval/AbstractSyntaxTree.kt
+++ b/src/commonMain/kotlin/com/notkamui/keval/AbstractSyntaxTree.kt
@@ -64,7 +64,7 @@ internal interface Node {
 }
 
 /**
- * An binary operator node
+ * A binary operator node
  *
  * @property left is its left child
  * @property op is the actual operator
diff --git a/src/commonMain/kotlin/com/notkamui/keval/Tokenizer.kt b/src/commonMain/kotlin/com/notkamui/keval/Tokenizer.kt
index b76a11f..ffdfa4e 100644
--- a/src/commonMain/kotlin/com/notkamui/keval/Tokenizer.kt
+++ b/src/commonMain/kotlin/com/notkamui/keval/Tokenizer.kt
@@ -47,7 +47,10 @@ private fun Sequence<String>.normalizeTokens(symbols: Map<String, KevalOperator>
                     ret.add(token)
                 } else {
                     throw KevalInvalidSymbolException(
-                        token, joinToString(""), currentPos, "comma can only be used in the context of a function"
+                        token,
+                        joinToString(""),
+                        currentPos,
+                        "comma can only be used in the context of a function"
                     )
                 }
             }
@@ -85,13 +88,20 @@ internal fun String.isKevalOperator(symbolsSet: Set<String>): Boolean = this in
  * @return the list of tokens
  * @throws KevalInvalidSymbolException if the expression contains an invalid symbol
  */
-internal fun String.tokenize(symbolsSet: Map<String, KevalOperator>): List<String> =
-    TOKENIZER_REGEX.findAll(this)
+internal fun String.tokenize(symbolsSet: Map<String, KevalOperator>): List<String> {
+    val constantsSet = symbolsSet.filter { it.value is KevalConstant }
+
+    val tokenizerRegex = if (constantsSet.isNotEmpty()) {
+        val constantsRegexString = constantsSet.keys.joinToString(separator = "|")
+        """(\d+\.\d+|\d+|$constantsRegexString|[a-zA-Z_]\w*|[^\w\s])"""
+    } else {
+        """(\d+\.\d+|\d+|[a-zA-Z_]\w*|[^\w\s])"""
+    }.toRegex()
+
+    return tokenizerRegex.findAll(this)
         .map(MatchResult::value)
         .filter(String::isNotBlank)
         .map { SANITIZE_REGEX.replace(it, "") }
         .normalizeTokens(symbolsSet)
-
-private val SANITIZE_REGEX = """\s+""".toRegex()
-
-private val TOKENIZER_REGEX = """(\d+\.\d+|\d+|[a-zA-Z_]\w*|[^\w\s])""".toRegex()
+}
+private val SANITIZE_REGEX = """\s+""".toRegex()
\ No newline at end of file
diff --git a/src/commonTest/kotlin/com/notkamui/keval/TokenizerTest.kt b/src/commonTest/kotlin/com/notkamui/keval/TokenizerTest.kt
index 0901b5d..3d83c37 100644
--- a/src/commonTest/kotlin/com/notkamui/keval/TokenizerTest.kt
+++ b/src/commonTest/kotlin/com/notkamui/keval/TokenizerTest.kt
@@ -103,4 +103,24 @@ class TokenizerTest {
         val nodes = "f(((1)))".tokenize(k.resourcesView())
         assertEquals("f(((1)))", nodes.joinToString(separator = ""))
     }
+
+    @Test
+    fun symbolsAndNumbers() {
+        listOf(
+            listOf("PI","9"),
+            listOf("9", "e"),
+            listOf("PI", "e"),
+            listOf("PI", "PI"),
+            listOf("PI", "e", "e", "PI")
+        ).forEach { tokenList ->
+            // Intersperses the assumed "*"
+            val expected = tokenList.dropLast(1).flatMap { listOf(it, "*") } + tokenList.last()
+            assertEquals(
+                expected,
+                tokenList
+                    .joinToString(separator = "")
+                    .tokenize(KevalBuilder.DEFAULT_RESOURCES)
+            )
+        }
+    }
 }