diff --git a/freedoi/resolver/forms.py b/freedoi/resolver/forms.py
index 822355c..26da0df 100644
--- a/freedoi/resolver/forms.py
+++ b/freedoi/resolver/forms.py
@@ -14,6 +14,12 @@ class PrefixForm(forms.ModelForm):
         if self.instance.pk:
             self.fields["prefix"].widget.attrs["readonly"] = True
 
+    def clean_suffix(self):
+        suffix = self.cleaned_data['suffix']
+        if not suffix.isdigit() or len(suffix) < 2:
+            raise forms.ValidationError('Suffix must be numeric and at least four digits long.')
+        return suffix
+
 
 class SuffixForm(forms.ModelForm):
     class Meta:
@@ -32,6 +38,12 @@ class SuffixForm(forms.ModelForm):
             self.fields["suffix"].widget.attrs["readonly"] = True
             self.fields["prefix"].widget.attrs["readonly"] = True
 
+    def clean_suffix(self):
+        suffix = self.cleaned_data['suffix']
+        if not suffix.isdigit() or len(suffix) < 4:
+            raise forms.ValidationError('Suffix must be numeric and at least four digits long.')
+        return suffix
+
 
 class SuffixApprovalForm(forms.ModelForm):
     class Meta:
@@ -52,6 +64,12 @@ class IdentifierForm(forms.ModelForm):
             self.fields["identifier"].widget.attrs["readonly"] = True
             self.fields["suffix"].widget.attrs["readonly"] = True
 
+    def clean_identifier(self):
+        identifier = self.cleaned_data['identifier']
+        if not all(c.isalnum() or c in '/-' for c in identifier):
+            raise forms.ValidationError('Identifier must be alphanumeric or contain / or - characters only.')
+        return identifier
+
 
 class PermissionForm(forms.ModelForm):
     class Meta:
diff --git a/freedoi/resolver/templates/resolver/identifier_form.html b/freedoi/resolver/templates/resolver/identifier_form.html
index c5d7564..562b314 100644
--- a/freedoi/resolver/templates/resolver/identifier_form.html
+++ b/freedoi/resolver/templates/resolver/identifier_form.html
@@ -4,6 +4,11 @@
 <div class="container mt-5">
   <h1>{% if form.instance.pk %}Edit{% else %}Create{% endif %} Identifier</h1>
   <form method="post">
+    {% if form.errors %}
+      <div class="alert alert-danger" role="alert">
+        {{ form.errors }}
+      </div>
+    {% endif %}
     {% csrf_token %} {{ form | crispy }}
     <button type="submit" class="btn btn-primary">Save</button>
   </form>
diff --git a/freedoi/resolver/templates/resolver/prefix_form.html b/freedoi/resolver/templates/resolver/prefix_form.html
index 9c752d0..6720d0c 100644
--- a/freedoi/resolver/templates/resolver/prefix_form.html
+++ b/freedoi/resolver/templates/resolver/prefix_form.html
@@ -3,6 +3,11 @@
 {% load crispy_forms_tags %} {% block content %}
 <h1>{% if form.instance.pk %}Edit{% else %}Create{% endif %} Prefix</h1>
 <form method="post">
+  {% if form.errors %}
+    <div class="alert alert-danger" role="alert">
+      {{ form.errors }}
+    </div>
+  {% endif %}
   {% csrf_token %} {{ form | crispy }}
   <input class="btn btn-primary" type="submit" value="Save" />
 </form>
diff --git a/freedoi/resolver/templates/resolver/suffix_form.html b/freedoi/resolver/templates/resolver/suffix_form.html
index 1085748..43e1d3a 100644
--- a/freedoi/resolver/templates/resolver/suffix_form.html
+++ b/freedoi/resolver/templates/resolver/suffix_form.html
@@ -4,6 +4,11 @@
 <div class="container mt-5">
   <h1>{% if form.instance.pk %}Edit{% else %}Create{% endif %} Suffix</h1>
   <form method="post">
+    {% if form.errors %}
+      <div class="alert alert-danger" role="alert">
+        {{ form.errors }}
+      </div>
+    {% endif %}
     {% csrf_token %} {{ form | crispy }}
     <p class="text-muted">Please make sure to include a full description of
       your intended use of the suffix in the "Description" field. Your request