diff --git a/packages/jsii/lib/assembler.ts b/packages/jsii/lib/assembler.ts
index 672db268af..082c525ee9 100644
--- a/packages/jsii/lib/assembler.ts
+++ b/packages/jsii/lib/assembler.ts
@@ -162,14 +162,21 @@ export class Assembler implements Emitter {
      *
      * @returns the de-referenced type, if it was found, otherwise ``undefined``.
      */
-    private _dereference(ref: spec.NamedTypeReference): spec.Type | undefined {
+    private _dereference(ref: spec.NamedTypeReference, referencingNode: ts.Node): spec.Type | undefined {
         const [assm, ] = ref.fqn.split('.');
+        let type;
         if (assm === this.projectInfo.name) {
-            return this._types[ref.fqn];
+            type = this._types[ref.fqn];
         } else {
             const assembly = this.projectInfo.transitiveDependencies.find(dep => dep.name === assm);
-            return assembly && assembly.types && assembly.types[ref.fqn];
+            type = assembly && assembly.types && assembly.types[ref.fqn];
         }
+
+        if (!type) {
+            this._diagnostic(referencingNode, ts.DiagnosticCategory.Error, `Unable to resolve referenced type '${ref.fqn}'. Missing export?`);
+        }
+
+        return type;
     }
 
     private _diagnostic(node: ts.Node | null, category: ts.DiagnosticCategory, messageText: string) {
@@ -206,7 +213,7 @@ export class Assembler implements Emitter {
             return `unknown.${typeName}`;
         }
         const fqn = `${pkg.name}.${typeName}`;
-        if (pkg.name !== this.projectInfo.name && !this._dereference({ fqn })) {
+        if (pkg.name !== this.projectInfo.name && !this._dereference({ fqn }, type.symbol.valueDeclaration)) {
             this._diagnostic(type.symbol.valueDeclaration,
                              ts.DiagnosticCategory.Error,
                              `Use of foreign type not present in the ${pkg.name}'s assembly: ${fqn}`);
@@ -314,7 +321,8 @@ export class Assembler implements Emitter {
                 continue;
             }
             this._defer(() => {
-                if (!spec.isClassType(this._dereference(ref))) {
+                const deref = this._dereference(ref, base.symbol.valueDeclaration);
+                if (deref && !spec.isClassType(deref)) {
                     this._diagnostic(base.symbol.valueDeclaration,
                                     ts.DiagnosticCategory.Error,
                                     `Base type of ${jsiiType.fqn} is not a class (${spec.describeTypeReference(ref)})`);
@@ -340,7 +348,8 @@ export class Assembler implements Emitter {
                     continue;
                 }
                 this._defer(() => {
-                    if (!spec.isInterfaceType(this._dereference(typeRef))) {
+                    const deref = this._dereference(typeRef, expression);
+                    if (deref && !spec.isInterfaceType(deref)) {
                         this._diagnostic(expression,
                                         ts.DiagnosticCategory.Error,
                                         `Implements clause of ${jsiiType.fqn} uses ${spec.describeTypeReference(typeRef)} as an interface`);
@@ -393,17 +402,15 @@ export class Assembler implements Emitter {
             }
         } else if (jsiiType.base) {
             this._defer(() => {
-                const baseType = this._dereference(jsiiType.base!);
-                if (!baseType) {
-                    this._diagnostic(type.symbol.valueDeclaration,
-                                    ts.DiagnosticCategory.Error,
-                                    `Unable to resolve type ${jsiiType.base!.fqn} (base type of ${jsiiType.fqn})`);
-                } else if (spec.isClassType(baseType)) {
-                    jsiiType.initializer = baseType.initializer;
-                } else {
-                    this._diagnostic(type.symbol.valueDeclaration,
-                        ts.DiagnosticCategory.Error,
-                        `Base type of ${jsiiType.fqn} (${jsiiType.base!.fqn}) is not a class`);
+                const baseType = this._dereference(jsiiType.base!, type.symbol.valueDeclaration);
+                if (baseType) {
+                    if (spec.isClassType(baseType)) {
+                        jsiiType.initializer = baseType.initializer;
+                    } else {
+                        this._diagnostic(type.symbol.valueDeclaration,
+                            ts.DiagnosticCategory.Error,
+                            `Base type of ${jsiiType.fqn} (${jsiiType.base!.fqn}) is not a class`);
+                    }
                 }
             });
         } else {
@@ -499,17 +506,13 @@ export class Assembler implements Emitter {
                 continue;
             }
             this._defer(() => {
-                if (!spec.isInterfaceType(this._dereference(ref))) {
-                    const baseType = this._dereference(ref);
-                    if (baseType) {
-                        this._diagnostic(base.symbol.valueDeclaration,
-                                        ts.DiagnosticCategory.Error,
-                                        `Base type of ${jsiiType.fqn} is not an interface (${baseType.kind} ${spec.describeTypeReference(ref)})`);
-                    } else {
-                        this._diagnostic(base.symbol.valueDeclaration,
-                            ts.DiagnosticCategory.Error,
-                            `Base type of ${jsiiType.fqn} could not be resolved (${spec.describeTypeReference(ref)})`);
-                    }
+                const baseType = this._dereference(ref, base.symbol.valueDeclaration);
+                if (baseType && !spec.isInterfaceType(baseType)) {
+                    // tslint:disable:max-line-length
+                    this._diagnostic(base.symbol.valueDeclaration,
+                                    ts.DiagnosticCategory.Error,
+                                    `Base type of ${jsiiType.fqn} is not an interface (${baseType.kind} ${spec.describeTypeReference(ref)})`);
+                    // tslint:enable:max-line-length
                 }
             });
             if (jsiiType.interfaces) {
diff --git a/packages/jsii/test/negatives/neg.deref-error.ts b/packages/jsii/test/negatives/neg.deref-error.ts
new file mode 100644
index 0000000000..a98d479ee3
--- /dev/null
+++ b/packages/jsii/test/negatives/neg.deref-error.ts
@@ -0,0 +1,9 @@
+///!MATCH_ERROR: Unable to resolve referenced type 'Base'. Missing export?
+
+class Base {
+
+}
+
+export class Derived extends Base {
+
+}
\ No newline at end of file