diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index da7823fddf2..d6358dd8856 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2020-11-23  Simon Marchi  <simon.marchi@efficios.com>
+
+	* lib/gdb.exp (gdb_assert): Show error message on error.
+
 2020-11-23  Tom de Vries  <tdevries@suse.de>
 
 	* gdb.ada/enum_idx_packed.exp: Limit setup_kfail to gnat 9 and 10.
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index c42933b3f41..f2954fd5192 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -1728,7 +1728,14 @@ proc gdb_assert { condition {message ""} } {
     }
 
     set code [catch {uplevel 1 expr $condition} res]
-    if {$code != 0 || !$res} {
+    if {$code == 1} {
+	# If code is 1 (TCL_ERROR), it means evaluation failed and res contains
+	# an error message.  Print the error message, and set res to 0 since we
+	# want to return a boolean.
+	warning "While evaluating expression in gdb_assert: $res"
+	unresolved $message
+	set res 0
+    } elseif { !$res } {
 	fail $message
     } else {
 	pass $message