diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 07da6c790b63..6fdf073093a6 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -122,6 +122,7 @@ perf-y += vsprintf.o
 perf-y += units.o
 perf-y += time-utils.o
 perf-y += expr-bison.o
+perf-y += expr.o
 perf-y += branch.o
 perf-y += mem2node.o
 
diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
new file mode 100644
index 000000000000..816b23b2068a
--- /dev/null
+++ b/tools/perf/util/expr.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <assert.h>
+#include "expr.h"
+
+/* Caller must make sure id is allocated */
+void expr__add_id(struct parse_ctx *ctx, const char *name, double val)
+{
+	int idx;
+
+	assert(ctx->num_ids < MAX_PARSE_ID);
+	idx = ctx->num_ids++;
+	ctx->ids[idx].name = name;
+	ctx->ids[idx].val = val;
+}
+
+void expr__ctx_init(struct parse_ctx *ctx)
+{
+	ctx->num_ids = 0;
+}
diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
index 7d226241f1d7..7cea8b7c3a5c 100644
--- a/tools/perf/util/expr.y
+++ b/tools/perf/util/expr.y
@@ -6,7 +6,6 @@
 #define IN_EXPR_Y 1
 #include "expr.h"
 #include "smt.h"
-#include <assert.h>
 #include <string.h>
 
 #define MAXIDLEN 256
@@ -169,21 +168,6 @@ static int expr__lex(YYSTYPE *res, const char **pp)
 	return tok;
 }
 
-/* Caller must make sure id is allocated */
-void expr__add_id(struct parse_ctx *ctx, const char *name, double val)
-{
-	int idx;
-	assert(ctx->num_ids < MAX_PARSE_ID);
-	idx = ctx->num_ids++;
-	ctx->ids[idx].name = name;
-	ctx->ids[idx].val = val;
-}
-
-void expr__ctx_init(struct parse_ctx *ctx)
-{
-	ctx->num_ids = 0;
-}
-
 static bool already_seen(const char *val, const char *one, const char **other,
 			 int num_other)
 {