diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index c6f41c4ca..fb7fc3ddb 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -3032,9 +3032,9 @@ static RegisterPrimOp primop_foldlStrict({
     .doc = R"(
       Reduce a list by applying a binary operator, from left to right,
       e.g. `foldl' op nul [x0 x1 x2 ...] = op (op (op nul x0) x1) x2)
-      ...`. The operator is applied strictly, i.e., its arguments are
-      evaluated first. For example, `foldl' (x: y: x + y) 0 [1 2 3]`
-      evaluates to 6.
+      ...`. For example, `foldl' (x: y: x + y) 0 [1 2 3]` evaluates to 6.
+      The return value of each application of `op` is evaluated immediately,
+      even for intermediate values.
     )",
     .fun = prim_foldlStrict,
 });
diff --git a/tests/lang/eval-fail-foldlStrict-strict-op-application.nix b/tests/lang/eval-fail-foldlStrict-strict-op-application.nix
new file mode 100644
index 000000000..1620cc76e
--- /dev/null
+++ b/tests/lang/eval-fail-foldlStrict-strict-op-application.nix
@@ -0,0 +1,5 @@
+# Tests that the result of applying op is forced even if the value is never used
+builtins.foldl'
+  (_: f: f null)
+  null
+  [ (_: throw "Not the final value, but is still forced!") (_: 23) ]
diff --git a/tests/lang/eval-okay-foldlStrict-lazy-elements.exp b/tests/lang/eval-okay-foldlStrict-lazy-elements.exp
new file mode 100644
index 000000000..d81cc0710
--- /dev/null
+++ b/tests/lang/eval-okay-foldlStrict-lazy-elements.exp
@@ -0,0 +1 @@
+42
diff --git a/tests/lang/eval-okay-foldlStrict-lazy-elements.nix b/tests/lang/eval-okay-foldlStrict-lazy-elements.nix
new file mode 100644
index 000000000..c666e07f3
--- /dev/null
+++ b/tests/lang/eval-okay-foldlStrict-lazy-elements.nix
@@ -0,0 +1,9 @@
+# Tests that the rhs argument of op is not forced unconditionally
+let
+  lst = builtins.foldl'
+    (acc: x: acc ++ [ x ])
+    [ ]
+    [ 42 (throw "this shouldn't be evaluated") ];
+in
+
+builtins.head lst
diff --git a/tests/lang/eval-okay-foldlStrict-lazy-initial-accumulator.exp b/tests/lang/eval-okay-foldlStrict-lazy-initial-accumulator.exp
new file mode 100644
index 000000000..d81cc0710
--- /dev/null
+++ b/tests/lang/eval-okay-foldlStrict-lazy-initial-accumulator.exp
@@ -0,0 +1 @@
+42
diff --git a/tests/lang/eval-okay-foldlStrict-lazy-initial-accumulator.nix b/tests/lang/eval-okay-foldlStrict-lazy-initial-accumulator.nix
new file mode 100644
index 000000000..abcd5366a
--- /dev/null
+++ b/tests/lang/eval-okay-foldlStrict-lazy-initial-accumulator.nix
@@ -0,0 +1,6 @@
+# Checks that the nul value for the accumulator is not forced unconditionally.
+# Some languages provide a foldl' that is strict in this argument, but Nix does not.
+builtins.foldl'
+  (_: x: x)
+  (throw "This is never forced")
+  [ "but the results of applying op are" 42 ]