diff --git a/api/handler/get.go b/api/handler/get.go
index 615f7f0..4c3bf38 100644
--- a/api/handler/get.go
+++ b/api/handler/get.go
@@ -231,17 +231,24 @@ func (h *handler) GetObjectHandler(w http.ResponseWriter, r *http.Request) {
 
 func checkPreconditions(info *data.ObjectInfo, args *conditionalArgs) error {
 	if len(args.IfMatch) > 0 && args.IfMatch != info.HashSum {
-		return errors.GetAPIError(errors.ErrPreconditionFailed)
+		return fmt.Errorf("%w: etag mismatched: '%s', '%s'", errors.GetAPIError(errors.ErrPreconditionFailed), args.IfMatch, info.HashSum)
 	}
 	if len(args.IfNoneMatch) > 0 && args.IfNoneMatch == info.HashSum {
-		return errors.GetAPIError(errors.ErrNotModified)
+		return fmt.Errorf("%w: etag matched: '%s', '%s'", errors.GetAPIError(errors.ErrNotModified), args.IfNoneMatch, info.HashSum)
 	}
 	if args.IfModifiedSince != nil && info.Created.Before(*args.IfModifiedSince) {
-		return errors.GetAPIError(errors.ErrNotModified)
+		return fmt.Errorf("%w: not modified since '%s', last modified '%s'", errors.GetAPIError(errors.ErrNotModified),
+			args.IfModifiedSince.Format(time.RFC3339), info.Created.Format(time.RFC3339))
 	}
 	if args.IfUnmodifiedSince != nil && info.Created.After(*args.IfUnmodifiedSince) {
+		// https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetObject.html#API_GetObject_RequestSyntax
+		// If both of the If-Match and If-Unmodified-Since headers are present in the request as follows:
+		// If-Match condition evaluates to true, and;
+		// If-Unmodified-Since condition evaluates to false;
+		// then, S3 returns 200 OK and the data requested.
 		if len(args.IfMatch) == 0 {
-			return errors.GetAPIError(errors.ErrPreconditionFailed)
+			return fmt.Errorf("%w: modified since '%s', last modified '%s'", errors.GetAPIError(errors.ErrPreconditionFailed),
+				args.IfUnmodifiedSince.Format(time.RFC3339), info.Created.Format(time.RFC3339))
 		}
 	}
 
@@ -251,8 +258,8 @@ func checkPreconditions(info *data.ObjectInfo, args *conditionalArgs) error {
 func parseConditionalHeaders(headers http.Header) (*conditionalArgs, error) {
 	var err error
 	args := &conditionalArgs{
-		IfMatch:     headers.Get(api.IfMatch),
-		IfNoneMatch: headers.Get(api.IfNoneMatch),
+		IfMatch:     strings.Trim(headers.Get(api.IfMatch), "\""),
+		IfNoneMatch: strings.Trim(headers.Get(api.IfNoneMatch), "\""),
 	}
 
 	if args.IfModifiedSince, err = parseHTTPTime(headers.Get(api.IfModifiedSince)); err != nil {
diff --git a/api/handler/get_test.go b/api/handler/get_test.go
index 22c7784..996dc2e 100644
--- a/api/handler/get_test.go
+++ b/api/handler/get_test.go
@@ -2,6 +2,7 @@ package handler
 
 import (
 	"bytes"
+	stderrors "errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -149,7 +150,11 @@ func TestPreconditions(t *testing.T) {
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			actual := checkPreconditions(tc.info, tc.args)
-			require.Equal(t, tc.expected, actual)
+			if tc.expected == nil {
+				require.NoError(t, actual)
+			} else {
+				require.True(t, stderrors.Is(actual, tc.expected), tc.expected, actual)
+			}
 		})
 	}
 }
diff --git a/api/handler/head_test.go b/api/handler/head_test.go
index d0c1225..2936ceb 100644
--- a/api/handler/head_test.go
+++ b/api/handler/head_test.go
@@ -27,10 +27,14 @@ func TestConditionalHead(t *testing.T) {
 	tc.Handler().HeadObjectHandler(w, r)
 	assertStatus(t, w, http.StatusOK)
 	etag := w.Result().Header.Get(api.ETag)
+	etagQuoted := "\"" + etag + "\""
 
 	headers := map[string]string{api.IfMatch: etag}
 	headObject(t, tc, bktName, objName, headers, http.StatusOK)
 
+	headers = map[string]string{api.IfMatch: etagQuoted}
+	headObject(t, tc, bktName, objName, headers, http.StatusOK)
+
 	headers = map[string]string{api.IfMatch: "etag"}
 	headObject(t, tc, bktName, objName, headers, http.StatusPreconditionFailed)
 
@@ -50,6 +54,9 @@ func TestConditionalHead(t *testing.T) {
 	headers = map[string]string{api.IfNoneMatch: etag}
 	headObject(t, tc, bktName, objName, headers, http.StatusNotModified)
 
+	headers = map[string]string{api.IfNoneMatch: etagQuoted}
+	headObject(t, tc, bktName, objName, headers, http.StatusNotModified)
+
 	headers = map[string]string{api.IfNoneMatch: "etag"}
 	headObject(t, tc, bktName, objName, headers, http.StatusOK)