diff --git a/kcms/fonts/fonts.h b/kcms/fonts/fonts.h
--- a/kcms/fonts/fonts.h
+++ b/kcms/fonts/fonts.h
@@ -153,6 +153,7 @@
     void save() override;
     void defaults() override;
     Q_INVOKABLE void adjustAllFonts();
+    Q_INVOKABLE void adjustFont(const QFont &font, const QString &category);
 
 Q_SIGNALS:
     void fontsHaveChanged();
diff --git a/kcms/fonts/fonts.cpp b/kcms/fonts/fonts.cpp
--- a/kcms/fonts/fonts.cpp
+++ b/kcms/fonts/fonts.cpp
@@ -653,37 +653,91 @@
     return m_fontAASettings->isDefaults();
 }
 
+// if the styleName property is empty, QFontDialog will always select
+// the first style in the list; for more details see:
+// https://phabricator.kde.org/D27735 and https://phabricator.kde.org/D27785
+QFont setRegularFontStyle(const QFont &font)
+{
+    QFont f(font);
+    QFontDatabase fdb;
+    const QStringList styles = fdb.styles(f.family());
+    for (const QString &s : styles) {
+        if (s == QLatin1String("Regular")
+            || s == QLatin1String("Normal")
+            || s == QLatin1String("Book")
+            || s == QLatin1String("Roman")) {
+            f.setStyleName(s);
+            return f;
+        }
+    }
+    return font;
+}
+
+void KFonts::adjustFont(const QFont &font, const QString &category)
+{
+    QFont f(font);
+    if (font.styleName().isEmpty() && font.weight() == QFont::Normal) {
+        f = setRegularFontStyle(font);
+    }
+
+    bool ok = false;
+    QFont selFont = QFontDialog::getFont(&ok, f, nullptr, i18n("Select Font"));
+
+    if (ok && !m_settings->isImmutable(category)) {
+        if (category == QLatin1String("font")) {
+            m_settings->setFont(selFont);
+        } else if (category == QLatin1String("menuFont")) {
+            m_settings->setMenuFont(selFont);
+        } else if (category == QLatin1String("toolBarFont")) {
+            m_settings->setToolBarFont(selFont);
+        } else if (category == QLatin1String("activeFont")) {
+            m_settings->setActiveFont(selFont);
+        } else if (category == QLatin1String("smallestReadableFont")) {
+            m_settings->setSmallestReadableFont(selFont);
+        } else if (category == QLatin1String("fixed")) {
+            m_settings->setFixed(selFont);
+        }
+    }
+}
+
 void KFonts::adjustAllFonts()
 {
+    QFont f(m_settings->font());
+    if (f.styleName().isEmpty() && f.weight() == QFont::Normal) {
+        f = setRegularFontStyle(f);
+    }
+
     bool ok = false;
-    QFont font = QFontDialog::getFont(&ok, m_settings->font(), nullptr, i18n("Select Font"));
+    QFont selFont = QFontDialog::getFont(&ok, f, nullptr, i18n("Select Font"));
 
     if (ok) {
         if (!m_settings->isImmutable("font")) {
-            m_settings->setFont(font);
+            m_settings->setFont(selFont);
         }
         if (!m_settings->isImmutable("menuFont")) {
-            m_settings->setMenuFont(font);
+            m_settings->setMenuFont(selFont);
         }
         if (!m_settings->isImmutable("toolBarFont")) {
-            m_settings->setToolBarFont(font);
+            m_settings->setToolBarFont(selFont);
         }
         if (!m_settings->isImmutable("activeFont")) {
-            m_settings->setActiveFont(font);
+            m_settings->setActiveFont(selFont);
         }
         if (!m_settings->isImmutable("smallestReadableFont")) {
-            m_settings->setSmallestReadableFont(font);
+            m_settings->setSmallestReadableFont(selFont);
         }
 
-        // Try to find a fixed-width/monspace font from the font family the user selected, e.g.:
+        // Try to find a fixed-width/monospace font from the font family the user selected, e.g.:
         // "Noto Sans" -> "Noto Sans Mono", "Ubuntu" -> "Ubuntu Mono"
         // we take the first one that comes along, e.g. "Noto Sans Mono" _not_ "Noto Sans Mono Blk"
+        // N.B. this a best effort kind of hack, the user can still select whatever fixed-width font
+        // he prefers afterwards
         QFontDatabase fdb;
         const QStringList fontFamilies = fdb.families();
         QString mono;
         for (const QString &family : fontFamilies) {
             // QString::endsWith() is cheaper than contains(), so try it first
-           if (family.startsWith(font.family())
+           if (family.startsWith(selFont.family())
                && (family.endsWith(QLatin1String("Mono"))
                    || family.contains(QLatin1String("Mono")))) {
                 mono = family;
diff --git a/kcms/fonts/package/contents/ui/FontWidget.qml b/kcms/fonts/package/contents/ui/FontWidget.qml
--- a/kcms/fonts/package/contents/ui/FontWidget.qml
+++ b/kcms/fonts/package/contents/ui/FontWidget.qml
@@ -57,11 +57,8 @@
             Kirigami.MnemonicData.enabled: false
             focus: true
             onClicked: {
-                fontDialog.adjustAllFonts = false;
-                fontDialog.currentCategory = root.category
-                fontDialog.font = root.font;
-                fontDialog.currentFont = root.font;
-                fontDialog.open()
+                fontDialog.adjustAllFonts = false
+                kcm.adjustFont(root.font, root.category)
             }
             QtControls.ToolTip {
                 visible: parent.hovered
diff --git a/kcms/fonts/package/contents/ui/main.qml b/kcms/fonts/package/contents/ui/main.qml
--- a/kcms/fonts/package/contents/ui/main.qml
+++ b/kcms/fonts/package/contents/ui/main.qml
@@ -264,9 +264,9 @@
                 property bool adjustAllFonts: false
                 onAccepted: {
                     if (adjustAllFonts) {
-                        kcm.adjustAllFonts(font);
+                        kcm.adjustAllFonts()
                     } else {
-                        kcm.fontsSettings[currentCategory] = font;
+                        kcm.adjustFont(font, currentCategory)
                     }
                 }
             }