diff --git a/src/frontend/variable.c b/src/frontend/variable.c
index 03523cdf5..cb928b1e6 100644
--- a/src/frontend/variable.c
+++ b/src/frontend/variable.c
@@ -678,7 +678,7 @@ span_var_expr(char *t)
     int parenthesis = 0;
     int brackets = 0;
 
-    while (*t && (isalphanum(*t) || strchr(VALIDCHARS, *t)))
+    while (*t && (isalnum(*t) || strchr(VALIDCHARS, *t)))
         switch (*t++)
         {
         case '[':
@@ -879,7 +879,7 @@ vareval(char *string)
             char *t = ++range;
             if (*t == '&')
                 t++;
-            while (isalphanum(*t))
+            while (isalnum(*t))
                 t++;
             *t = '\0';
             r = vareval(range);
diff --git a/src/include/ngspice/macros.h b/src/include/ngspice/macros.h
index c9fc389e6..d568cbd93 100644
--- a/src/include/ngspice/macros.h
+++ b/src/include/ngspice/macros.h
@@ -24,7 +24,6 @@
 
 #define eq(a,b)  (!strcmp((a), (b)))
 #define eqc(a,b)  (cieq((a), (b)))
-#define isalphanum(c)   (isalpha(c) || isdigit(c))
 #define hexnum(c) ((((c) >= '0') && ((c) <= '9')) ? ((c) - '0') : ((((c) >= \
         'a') && ((c) <= 'f')) ? ((c) - 'a' + 10) : ((((c) >= 'A') && \
         ((c) <= 'F')) ? ((c) - 'A' + 10) : 0)))