diff --git a/src/expr.c b/src/expr.c
index a08f0e03..fa2aa39a 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -426,7 +426,7 @@ get_var(expr_node *node, Value *ans, int *nonconst)
         return E_NOSUCH_VAR;
     }
     v->used_since_set = 1;
-    if (v->nonconstant) {
+    if (!v->is_constant) {
         nonconst_debug(*nonconst, tr("Global variable `%s' makes expression non-constant"), str);
         *nonconst = 1;
     }
diff --git a/src/types.h b/src/types.h
index 42d0ca65..590d8c3c 100644
--- a/src/types.h
+++ b/src/types.h
@@ -105,7 +105,7 @@ typedef struct var {
     struct hash_link link;
     char name[VAR_NAME_LEN+1];
     char preserve;
-    char nonconstant;
+    char is_constant;
     char used_since_set;
     Value v;
 } Var;
diff --git a/src/var.c b/src/var.c
index 7c851041..42b77b09 100644
--- a/src/var.c
+++ b/src/var.c
@@ -599,7 +599,7 @@ int SetVar(char const *str, Value const *val, int nonconst_expr)
 
     DestroyValue(v->v);
     v->v = *val;
-    v->nonconstant = nonconst_expr;
+    v->is_constant = ! nonconst_expr;
     v->used_since_set = 0;
     return OK;
 }
@@ -653,8 +653,8 @@ int DoSet (Parser *p)
         }
         var = FindVar(DBufValue(&buf), 0);
         if (var) {
-            nonconst_debug(var->nonconstant, tr("Potential variable assignment considered non-constant because of context"));
-            var->nonconstant = 1;
+            nonconst_debug(!var->is_constant, tr("Potential variable assignment considered non-constant because of context"));
+            var->is_constant = 0;
         }
         DBufFree(&buf);
         return OK;
@@ -787,7 +787,7 @@ int DoDump(ParsePtr p)
                 fprintf(ErrFp, "%s  ", v->name);
                 PrintValue(&(v->v), ErrFp);
                 if (dump_constness) {
-                    if (!v->nonconstant) {
+                    if (v->is_constant) {
                         fprintf(ErrFp, " <const>");
                     }
                 }
@@ -822,7 +822,7 @@ void DumpVarTable(int dump_constness)
         fprintf(ErrFp, "%s  ", v->name);
         PrintValue(&(v->v), ErrFp);
         if (dump_constness) {
-            if (!v->nonconstant) {
+            if (v->is_constant) {
                 fprintf(ErrFp, " <const>");
             }
         }