diff --git a/Makefile b/Makefile
index bab5001ed..499007884 100644
--- a/Makefile
+++ b/Makefile
@@ -3,6 +3,7 @@ CURRENT_RUST_VERSION := $(shell rustc -V | sed -E 's/rustc ([0-9]+\.[0-9]+\.[0-9
 CURRENT_RUST_TARGET := $(shell rustc -vV | grep host | cut -d ' ' -f 2)
 RUSTUP := $(shell command -v rustup 2> /dev/null)
 UNAME_S := $(shell uname -s)
+MINIMUM_TCL_VERSION := 8.6
 
 # Executable used to execute the compatibility tests.
 SQLITE_EXEC ?= scripts/limbo-sqlite3
@@ -27,6 +28,17 @@ check-rust-version:
 	fi
 .PHONY: check-rust-version
 
+check-tcl-version:
+	@printf '%s\n' \
+		'set need "$(MINIMUM_TCL_VERSION)"' \
+		'set have [info patchlevel]' \
+		'if {[package vcompare $$have $$need] < 0} {' \
+		'    puts stderr "tclsh $$have found — need $$need+"' \
+		'    exit 1' \
+		'}' \
+	| tclsh
+.PHONY: check-tcl-version
+
 check-wasm-target:
 	@echo "Checking wasm32-wasi target..."
 	@if ! rustup target list | grep -q "wasm32-wasi (installed)"; then \
@@ -67,7 +79,7 @@ test-shell: limbo uv-sync-test
 	RUST_LOG=$(RUST_LOG) SQLITE_EXEC=$(SQLITE_EXEC) uv run --project limbo_test test-shell
 .PHONY: test-shell
 
-test-compat:
+test-compat: check-tcl-version
 	RUST_LOG=$(RUST_LOG) SQLITE_EXEC=$(SQLITE_EXEC) ./testing/all.test
 .PHONY: test-compat