diff --git a/mlir/include/mlir-c/AffineExpr.h b/mlir/include/mlir-c/AffineExpr.h
--- a/mlir/include/mlir-c/AffineExpr.h
+++ b/mlir/include/mlir-c/AffineExpr.h
@@ -50,7 +50,7 @@
 
 /// Returns `true` if the given affine expression is a null expression. Note
 /// constant zero is not a null expression.
-inline bool mlirAffineExprIsNull(MlirAffineExpr affineExpr) {
+inline static bool mlirAffineExprIsNull(MlirAffineExpr affineExpr) {
   return affineExpr.ptr == NULL;
 }